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: Medicine
Which of the following is given to treat thrombocytopenia secondary to anti-cancer therapy and is known to stimulate progenitor megakaryocytes 
Select and explain. 
A. Filgrastim, B. Oprelvekin, C. Erythropoietin, D. Anagrelide
B: Oprelvekin
Answer: B: Oprelvekin 
Explanation: Ans. is 'b' i.e., Oprelvekin