A 45 year old female patient presents with symptoms of easy bruisabilty and frequent headaches. Physical examination shows moderate splenomegaly. Blood counts show a normal leucocyte count and platelet count of 1000 × 103/cu mm. The leukocyte alkaline phosphatase score is normal. Which of the following is the drug of choice for the treatment of this patient?
Hydroxy urea Radioactive phosphorous Anagrelide Interferon alpha