This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Crystal Ahropathy, Subject name: Medicine
In a patient with gouty ahritis,synol fluid aspiration was done,strongly negative birefringent needle shaped crystals were seen under polarized light .These crystals are composed of which of the following ? 
Select and explain. 
A. Monosodium urate, B. Calcium pyrophosphate, C. Sodium pyrophosphate, D. Homogentisic acid
A: Monosodium urate
Answer: A: Monosodium urate 
Explanation: Crystals of monosodium urate are needle-shaped, 5-25 mm in length, and strongly negatively bifringent under polarized light. Crystallization of monosodium urate in synol fluid and tissues results in a dramatic inflammatory response characterized by erythema, edema, and intense pain. Double contour cailage line on USG is seen