Which statement is correct for the reaction below?
4X+Z yields 2R+2S
A: The rate of formation of R is one-half the rate of the disappearance of Z.
B: The rate of disappearance of Z is one-fourth of the rate of disappearance of X.
C: The rate of formation of R is double the rate of formation of S.
D: The rate of formation of S is double the rate of disappearance of X.