What is the inductance of three 10-millihenry inductors connected in parallel?

Inductors connected in parallel combine in the same way that resistors do. When you have multiple inductors of the exact same value in parallel, you can find the total inductance simply by dividing the value of one inductor by the total number of inductors. In this case, you have three 10-millihenry inductors. Dividing 10 mH by 3 gives a total inductance of approximately 3.33 millihenries, which matches the 3.3 millihenry option. The 30 millihenry option is incorrect because it represents what would happen if the inductors were wired in series. The options with "henries" are distractors designed to catch you overlooking the metric prefix.