Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R) :

Assertion (A) : Hugo deVries believed that it is mutation (large difference arising suddenly in a population) which causes evolution and not the minor heritable variations that Darwin described in his theory.

Reason (R) : Evolution for Darwin was gradual, while deVries believed that single step large mutation caused speciation called saltation. 

In the light of above statements, choose the most appropriate answer from the options given below.