In a positive-feedback system where hormone A alters the amount of protein X,
A) a decrease in A always produces an increase in X, which results in an increase in A.
B) it is impossible to predict how A and X affect each other.
C) an increase in A always produces an increase in X, which results in an increase in A.
D) an increase in X always produces a decrease in A, which results in a decrease in X.
E) a decrease in X always causes a decrease in A, which causes an increase in X.
Answer: C