Sometimes, certain enzymes are associated with a particular organelle of the cell. Many times scientists have had to use ________________ centrifugation to separate different constituents of the cell. Following this procedure, you aliquot the fractions into separate test tubes, each correlating to a particular layer (or fraction) of your centrifugation end product. One way to help isolate an enzyme from among all the fractions collected is to assay for enzyme ___________. This will help delineate which fraction the enzyme is in, and even some of its properties.

Question

a. differential, activity
b. micro, presence
c. micor, products
d. swing-bucket, activity

I think the answer is "A" but I don't really have any solid reason for it.

Blank 1:

http://en.wikipedia.org/wiki/Differential_centrifugation

Blank 2:
http://en.wikipedia.org/wiki/Enzyme_activity