To answer the question above, use conversion factors and dimensional analysis. In this given, it is easier to use grams as the basis.
a. (2 centrigrams) x (1 gram / 100 centigrams) = 0.02 grams
b. 2 grams
c. (2 hectograms) x (1 gram / 0.01 hectogram) = 200 grams
d. (2 kilograms) x (1 gram / 0.001 kilogram) = 2000 grams
e. (2 milligrams) x (1 gram / 1000 millimeters) = 0.002 grams
Thus, the answer is 2 milligrams.