What is the minimum number of bits required to sample a signal with a range of 1 volt at a resolution of 1 millivolt?

Answer: D. 10 bits

1 V divided into 1 mV steps needs 1 V / 0.001 V = 1000 levels. 2^9 = 512 is too few and 2^10 = 1024 is enough, so 10 bits are required.

Tip: 2^10 = 1024, just over 1000.