In SDT We Represent Signal and Noise as a Pair

Multiple Choice

In SDT we represent signal and noise as a pair of distributions. Which of the following is a true statement concerning these distributions:

A) there is always some overlap between the distributions and the distributions are normal
B) there is no overlap between the distributions and the distributions are normal
C) there is always some overlap between the distributions are the distributions are not normal
D) there is overlap between the distributions and the distributions are normal