A 12-year-old healthy girl has some dizziness at synagogue. In your office, you find her to have a hemoglobin of 8 mg/dL, a white blood cell (WBC) count of 4000/μL, and a platelet count of 98,000/μL. Physical examination reveals an enlarged spleen. An x-ray of the femur is described as appearing to be an Erlenmeyer flask. Bone marrow examination shows abnormal cells. The diagnosis can be confirmed by measurement of activity of which of the following?
a) Acid alpha-glucosidase
b) Acid phosphatase
c) Beta-glucocerebrosidase
d) Hexosaminidase A