What is the role of mutations in creating variation in bird beak types?

In order for a bird's beak to evolve into different a types, a mutation must occur first.

Explanation:

All evolution relies on mutations or changes to the DNA. Bird beaks adapt to the environment to be better suited to obtain food. A bird that used to have a pointy beak for stabbing bugs might move to an area with an abundance of seeds. Their DNA mutates so that their offspring can have short beaks to pick up seeds.

i believe it is c: genes for body color and wing size are inherited separately from each parent.