(A) A reaction cannot become fast by itself unless a catalyst is added .
(R) A catalyst always increases the speed of a reaction.
A. If both (A) and (R) are true and (R) is the correct explanation of (A).
B. If both (A) and (R) are true but (R) is not the correct explanation of (A).
C. If (A) is correct but (R) is incorrect.
D. If (A) and (R) are both incorrect.
