For these I'm clueless. Please help

5) Function D(t) = (4t)/(0.01t^2+5.1). Given the concentration, D, of a drug in bloodstream where D is measured in micrograms per milliliter and t is minutes from the time the drug is taken. What's the maximum concentration of the drug found in bloodstream at any time?

A) 0.01 micrograms/ milliliters

B) 4 micrograms/ milliliters

C) 5.1 micrograms/ milliliters

D) 8.856 micrograms/ milliliters

E) 22.583 micrograms/ milliliters