Underground mammals, such as the ancestors of moles, are thought to have first evolved as the dinosaurs died out.

which effect of an environmental change does this best illustrate?
a. migration
b. loss of habitat
c. change in behavior
d. speciation

The correct option is D. Speciation

Explanation:

Speciation can be described as a process in which new species evolve from ancestral species. This evolutionary process might occur due to geographical separation of the species which is termed as Allopatric speciation. It might also occur due to the divergence and reproductive isolation of the ancestral species. Reproductive isolation means that organisms from the same species stop interbreeding. Such an evolutionary process is termed as Sympatric speciation.

dna is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).