Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
Elath Taen made mad music for the men of Mars. planet. And when Jared Haller sent to Earth for one of the Terrestial Intelligence, that silent efficient corps of trouble-shooters, something was definitely up. Ranson passed the conventional electric eye and a polite robot voice to a pocket that bulged unmistakably. "Ranson, Terrestial Intelligence." The special agent offered his card. "You sent to Earth a while ago for an operator?" mouth, and a species of terror within the shaggy-browed eyes. "Yes," said Jared Haller. "I sent for an operator. You got here quickly, Mr. Ranson!" ." Ranson wondered headquarters in New York hadn't known why a T.I. man was wanted on Mars ... but Haller was one of the few persons sufficiently important to have an operator sent without explanation as to why he was wanted. Ranson put it directly. "Why did you require the help of T.I., Mr. told what crime had taken place. This time Ranson applied the spur of silence. It worked. heart attack, his doctor said. You begin to see the set-up? Three men, each a vital power in M.B.C. gone within three weeks! And who's next? Who?" Jared Haller's eyes were bright with fear. "Music?" Ranson echoed. "Look here, Mr. Haller, you...." "It's all right." Jared Haller grinned crookedly. "I'm not insane. Yet. Look, Mr. Ranson! There's just one clue to these mysterious deaths! And that's the music! In each instance the servants told of hearing, silver knife plucking a cruel obligato on taut nerves, it was a thin dark snake writhing its endless coils into the room. Neither man moved. Ranson knew all the tricks of visual hypnotism, the brain, a strange unreasoning bloodlust grew with the savage beat of the wild music. Berserk rage sounded in each shivering note and Ranson felt an insane desire to run amok. To inflict pain, to see red blood flow, to kill ... kill! Blindly he whirled, groping for his gun, as the music rose in a frenzied death-wail. distorted his features, insane murder lurked in his eyes. The music was his master, and it was driving him to frenzy. "Kill!" the weird rhythm screamed, "Kill!" And Jared Haller obeyed. He snatched the flame-gun from his pocket, levelled it at Ranson. Whether it was the deadly melody outside, or the instinct of The end came with startling suddenness. Ranson, twisting his opponent's arm back, felt the searing blast of the flame-gun past his hand. Jared Haller, a ghastly blackened corpse, toppled to the floor. At that moment the lethal rhythm outside changed abruptly. From the disappeared among the twisting narrow streets. Bathed in cold sweat, Ranson stepped back into the room, where the still, terrible form of motioned to the two gray-uniformed patrolmen. "Take Mr. Ranson." And then Steve Ranson went into action. In one blinding burst of speed, he lunged across the desk, tore Captain Maxwell's pistol from its holster. Before the captain and the two patrolmen knew what had can try me for murder if you want, after I've done my job here!" Ranson took the key from the massive plastic door as he backed through the entrance. Once in the hall, he slammed the door shut, locked Maxwell and his men in the room. Then, dropping the gun into his pocket, he ran swiftly down the corridor to the main entrance of headquarters. In the hall a patrolman glanced at him suspiciously, halted him, but a wave of Ranson's T.I. card put the man aside. Free of headquarters, Ranson began to run. Only a few moments, he knew, before Maxwell and his men blasted a way to freedom, set out in pursuit. Like a lean gray shadow Ranson ran, twisting, dodging, among there was little danger, he felt, of patrolmen hunting for him at Haller's house. The captain had little faith in copybook maxims about the murderer returning to the scene of the crime. Ranson stood motionless for a moment as a canal boat swept by, then tube, and the head of it was large as a man's two fists and covered with small dials, gauges. This was the T.I.'s most cherished secret, the famous "electric bloodhound," by which criminals could be tracked. Ranson touched a lever and a tiny electric motor in the head of the cane hummed, drawing air up along the tube. He tapped the bank where Ranson tapped the cane carefully upon the ground, avoiding those places where he had stood. Few people crossed this overgrown embankment, and it was a safe bet that no one other than the strange musician had been there recently. The scent was a clear one, and the dials on the head of the cane read R-2340-B, the numerical classification of the upon sensitive nerve filaments, and they knew that any normal human can follow a trail of some strong odor such as perfumes, or gasoline, while animals, possessing more sensitive perceptions, can follow less distinct trails. To duplicate this mechanically had proven more Ranson now carried. As Ranson plunged further into the old Martian quarter, the trail grew more and more confused, crossed by scores of other trails left by passersby. He was forced to stop, cast about like a bloodhound, tapping every square foot of the street before the R-2340-B on the dial showed that he had once more picked up the faint elusive scent. Deeper and deeper Ranson plunged into the dark slums of Mercis. Smoky gambling dens, dives full of drunken spacehands and slim red-skinned At the end of an alley where the purple shadows lay like stagnant pools, Ranson paused. The alley was a cul-de-sac, which meant that the person he was trailing must have entered one of the houses. Very softly he tapped the long tube on the ground. Again with a hesitant swinging of dials, R-2340-B showed up, on the low step in front of one of the dilapidated, dome-shaped houses. Ranson's eyes narrowed. So the person who had played the mad murder melody had entered that house! Might still be there! Quickly he telescoped the "electric bloodhound," dropped it into his pocket, and drew his flame-gun. The old house was dark, with an air of morbid deadly calm about it. Ranson tried the door, found it locked. A quick spurt from his flame-gun melted the lock black fluid did not so much as waver at Ranson's entrance. Ranson gasped. The bizarre figure was that of Dr. Elath Taen, master-scientist, sought by the T.I. for years, in vain! Elath Taen, outlaw and renegade, whose sole desire was the extermination of all terrestials on Mars, a revival of the ancient glories of the red "Good evening, Mr. Ranson," Elath Taen smiled. "Had I known T.I. at Ranson. Quick as he was, the T.I. man was quicker. A spurt of "Well done, Mr. Ranson." Elath Taen nodded calmly. "Had the acid struck Taen! We're going to headquarters!" "Since you insist." Elath Taen removed his chemist's smock, began, very "Exactly, Mr. Ranson." Elath Taen smiled thinly. "Listen!" But his words held no force, and Elath Taen was nodding sleepily under Across the laboratory Elath Taen had slumped to the floor, a vague Taen, the laboratory, all faded into a kaleidoscopic whirl. Ranson felt

<question>:
How did Ranson find Elath Taen?

<options>:
A He analyzed his DNA.
B He found footprints.
C He followed his scent.
D He tracked the stolen "electric bloodhound."

<answer>:

C