Mutations that improve an individuals ability to
survive and reproduce are

Beneficial

Explanation:

Mutation is a sudden change that occurs in the gene sequences. Mutation can have both positive or negative effect on living organisms. It can lead to disorders and also one of the ways that causes evolution of the species. If the mutation, improves the individual's ability to improve their survival or reproduction then it is called as beneficial.

Due to mutation, the gene sequences changes due to which the amino acids encoded during the process of translation also changes. If different proteins are formed then the function that was supposed to be performed by the proteins of non-mutated genes varies.  

the answer is d.) homologous; have mammary glands

i think the answer would be d