This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Aggrecan in 
Select and explain. 
A. Receptor over platelets, B. A molecule present in osteoid tissue, C. Granules in leukocytes, D. Important component of cartilage
D: Important component of cartilage
Answer: D: Important component of cartilage 
Explanation: Aggrecan is the major proteoglycan component of cartilage. It is composed of several glycosaminoglycans (hyaluronic acid, chondroitin sulfate and keratin sulfate) and both link and core proteins.