Harmful or , is considered to be the source for new alleles and a main contributor to the diversity of life on earth. a) mitosis b) mutation c) transcription d) translation

Option B, Mutation

Explanation:

Genetic mutation causes diversity within the population of any species as it causes changes in genetic sequences.  The effect of such changes varies differently based on the point and time of their occurrence. Hence, mutation can be beneficial, non-beneficial and even neutral.  

Mostly these changes may be random or non-random in nature at the same time and even a single mutation can bring large effect. However, evolutionary changes are brought by accumulated effect of several mutations.  

Hence, option B is correct