Gene mutations can be caused by many things. These mutations are biologically important because they can be passed to the offspring if they occur in any cell of the body

can result in a new variety of gene combinations in the species

are always harmful and therefore help to eliminate weak traits

occur at a regular rate and therefore can be controlled

Can result in a new variety of gene combinations in the species

Explanation:

The third option is blatantly untrue- gene mutations are sometimes harmful, usually mundane and do nothing, and sometimes extremely helpful.

The fourth option is also untrue- genetic mutation is completely random.

This leaves us with the first two-

The first option is true, but it's not why genetic mutations are important, it's simply how they are passed on.

The second option is the awnser because gene diversity is extremely important in populations, and 'variety of gene combinations' is just another way to say gene diversity.