In a Positive-Feedback System Where Hormone a Alters the Amount

Multiple Choice

In a positive-feedback system where hormone A alters the amount of protein X,

A) an increase in A always produces an increase in X, which results in an increase in A.
B) an increase in X always produces a decrease in A, which results in a decrease in X.
C) a decrease in A always produces an increase in X, which results in an increase in A.
D) a decrease in X always causes a decrease in A, which causes an increase in X.
E) it is impossible to predict how A and X affect each other.