A certain electromagnet has 1000 turns of wire. How much current must flow through the coil in order to generate an mmf of 100 ampere-turns? A. 0.1 A B. 1000 A C. 10:00 AM D. 100 A E. None of the above

The correct answer is $\boxed{\text{D}}$.

The ampere-turn (At)

is a unit of magnetomotive force (mmf). It is defined as the product of the current (in amperes) and the number of turns (in turns) of a coil. The mmf of a coil is proportional to the current flowing through it, and the number of turns in the coil.

In this case, the coil has 1000 turns, and we are given that the mmf is 100 At. Therefore, the current flowing through the coil is $I = \frac{mmf}{N} = \frac{100 \text{ At}}{1000 \text{ turns}} = 0.1 \text{ A}$.

Option A is incorrect because it is too small. Option B is incorrect because it is too large. Option C is incorrect because it is not a unit of mmf. Option E is incorrect because it is not a number.