Lee already explained the math, but besides: if you want to convert X to Y, you have to start with X, don't you? Answers B and C already can't be right to convert farads into something else because they don't start with farads in the first place. (And by the way: the symbol for farad is a *capital* F, so it's µF for microfarad.)

The statement "Convert farads to microfarads by:" can be rewritten as "Given the capacitance of a capacitor in Farads, calculate the value of the same capacitance in units of microfarads by:" The thought process should be:- If you are given a capacitance value such as 2 Farads, how do you express the same value of capacitance in microfarads? If 1 Farad = 1 million uF, then 2 Farad = 2 million uF. You are merely using the derived unit "microfarad" to express the same value of capacitance as the SI unit "Farad". The capacitance value doesn't change, only the units do (and of course, the figure changes as the decimal point shifts along with the units). Therefore C is obviously incorrect because you were given the value in Farads. At this point, you can't "multiply microfarads by 10^6" because you don't have any microfarads to begin with.

1 farad / (10^6) ufarads = 1 1 farad = 10^6 ufarads To convert 5 farads to ufarads, MULTIPLY 5 FARADS x (10^6 uFARADS/1 farad) = 5 x 10^6 ufarads > to convert farads to ufarads, multiply farads by 10^6. (Answer A)