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

<passage>:
I've wet-nursed Shannon's Imperial Circus around the Triangle for eleven years, and I know. It's lousy, it's mangy, it's broken-down! grey-green eyes get sleepy, and hear the quarter-Earth-blood Martian girl wailing about love over by the battered piano, and watch the He said, "I don't think you understand." back. It sounded like he'd ripped the floor open, it was so quiet. I quivering and showing their teeth. The Martian girl screamed. ever met, and you couldn't see into those innocent blue eyes any more than you could see through sheet metal. I didn't like him. I didn't like him at all. But he had money. I said, Bucky got red around the ears. "Just a minute," he murmured, and ignored him. He went on, quietly, toil and boredom...." I said, "Sure, sure. But what was your idea?" He said, "Boss, Gertrude's actin' up again." "Gertrude be blowed," growled Bucky. "Can't you see I'm busy?" Gow's black eyes were unpleasant. "I'm tellin' you, Boss, Gertrude fit me for a coffin. "Okay! But Gertrude's unhappy. She's lonesome, "Gertrude?" "Yeah. She's kind of temperamental." Bucky took a quick drink. I finished for him. "She's the star attraction of our show, Mr. Beamish. A real blue-swamp Venusian Brothers, and she's much smaller than Gertrude." She was also much younger, but I didn't go into that. Gertrude may be wouldn't die on us, because without her we'd have a sicker-looking circus than even I could stand. . Well, well! The mystery surrounding the origin and species of the yelled. "You want to sit here till we all dry up and blow away?" !" red dust gritted in my teeth. weeks we'd come in at the front door. "Let's go see Gertrude." I didn't want to see Gertrude. I never got over feeling funny going a dim glow. Gow was evidently holding Gertrude's hand. We started down Our footsteps sounded loud and empty on the iron floor. I wasn't breathing and rustling in the dark, with the patient hatred walled then wiped the sweat off my forehead and cursed. The scream came again. A high, ragged, whistling screech like nothing this side of hell, ripping through the musty darkness. Gertrude, on the wailing wall. It had been quiet. Now every brute in the place let go at the same time. My stomach turned clear over. I called Gertrude every name I metallic clash nearly burst my eardrums, and the beasts shut up. Gow But they didn't quiet down. Not really. They were uneasy. You can feel Gow glared at us as we came up into the lantern light. "She's gettin' worse," he said. "She's lonesome." "That's tough," said Bucky Shannon. His grey-green eyes looked like an I looked at Gertrude. Her cage is the biggest and strongest in the tank I wouldn't know, of course, but Gertrude looks to me like she got stuck some place between a dinosaur and a grizzly bear, with maybe a little bird blood thrown in. Anyway, she's big. I couldn't help feeling sorry for her. She was crouched in the cage with her hands—yeah, hands—hanging over her knees and her snaky head sunk into her shoulders, looking out. Just looking. Not at anything. Her eyes were way back in deep horny pits, like cold green fire. mane, or crest, of coarse wide scales that ran from between her eyes clear down to her flat, short tail, burn all colors. She looked like old Mother Misery herself, from way back before time began. Gow said softly, "She wants a mate. And somebody better get her one." Bucky Shannon sniffled again. I said irritably, "Be reasonable, Gow! Nobody's ever seen a male cansin . There may not even be any." Gertrude screamed again. She didn't move, not even to raise her head. The sadness just built up inside her until it had to come out. That close, the screech was deafening, and it turned me all limp and cold inside. The loneliness, the sheer stark, simple pain.... Bucky Shannon began to cry. I snarled, "You'll have to snap her out of this, Gow. She's driving the rest of 'em nuts." turned to Gertrude. "I saved her life," he said. "When we bought her out of Hanak's wreck and everybody thought she was too hurt to live, I saved her. I know her. I can do things with her. But this time...." He shrugged. He was huge and tough and ugly, and his voice was like a woman's talking about a sick child. us. Bucky sobbed. "You were right, Jig," he mumbled. "Circus is no good. I know it. But it's all I got. I love it, Jig. Unnerstan' me? Like Gow there with Gertrude. She's ugly and no good, but he loves her. I love...." "Sure, sure," I told him. "Stop crying down my neck." I yelled, "Gow! Gow, the Vapor snakes! Gow—for God's sake!" and heavy. The noise burst suddenly in a deafening hell of moans and roars and shrieks, packed in tight by the metal walls, and above it all I could hear Gertrude's lonely, whistling scream. I thought, " Somebody's down here. Somebody let 'em out. Somebody wants " I tried to yell again. It strangled in my throat. I sobbed, and the sweat was thick and cold on me. Bucky moaned and kicked under me. I remember hanging on and thinking, "This is it. This is it, and oh God, I'm scared!" said, "Where's Shannon? How is he?" I hurt all over. I growled, "With that brain, son, you should go far. I said, "Skip it. The next time, just don't trip me up, that's all!" strong-man got hurt during the take-off, and the Mercurian cave-cat had kittens. Nobody would have minded that, only one of 'em had only four legs. It lived just long enough to scare that bunch of superstitious dopes out I snarled, "What do you want, with this lousy dog-and-pony show!" and While we passed the hatchway to the brute tank, I could hear Gertrude, screaming. standing in the mud with her arms up and her head thrown back, and her triangular mouth open like a thirsty dog. She didn't have anything on but her blue-green, hard scaled hide, and she was chuckling. It didn't sound nice. her jaw pulsed like a toad's, and her eyes were red. "The deep swamps are angry," she whispered. "Something has been taken. They are angry, and I smell death in the wind!" She turned away, laughing, and I cursed her, and my stomach was tight and cold. Bucky said, "Let's eat if they have a bar in this dump." who crawled and whimpered in the mud. " Cansin . Male. Only one. You don't know...! Take him back." "Where is it, Sam?" made a harsh strangling noise and fell across the table. Shannon stared at me. Beamish started to get indignant. "Shut up," I ," said a voice in my ear. "As if you didn't know."

<question>:
Why was Gertrude continuously screaming?

<options>:
A She was cramped in a much too small space.
B She missed her family.
C She was near starving.
D She was desperate for a mate

<answer>:

D