Final answer:
Mutation is the process that produces new alleles by causing changes in the DNA sequence, while fertilization and recombination shuffle existing alleles to create genetic variation.
Step-by-step explanation:
The process that leads to the production of new alleles is mutation. While fertilization combines existing alleles from two parents to produce a unique genetic combination in the offspring, it does not create new alleles. Recombination, which includes processes like genetic recombination and crossing over, shuffles existing alleles to create new combinations, but again, it does not produce new alleles. It's only through mutation—a change in the DNA sequence—that entirely new alleles can arise, providing a source of genetic variation in a population. Therefore, the correct answer to the question is b) Mutation.