An AND gate has 7 inputs, what is the only input word that produces a 1 output? A. 0 B. 1111 C. 1110000 D. 1111111 E. None of the above

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

An AND gate is a digital logic gate that implements logical conjunction. In other words, it produces a 1 output only if all of its inputs are 1.

The input word 1111111 is the only one that satisfies this condition, so it is the only input that produces a 1 output.

The other options are incorrect because they do not have all 1s in their input.

Option A, 0, has 0s in all of its inputs, so it will always produce a 0 output.

Option B, 1111, has 1s in all of its inputs except for the first input, so it will only produce a 1 output if the first input is also 1.

Option C, 1110000, has 1s in all of its inputs except for the first

Option E, None of the above, is incorrect because there is at least one input word that produces a 1 output, namely 1111111.