Bromination occurs on alkene functional groups, but not on alkenes found within aromatic functional groups, such as the phenyl ring of cinnamic acid. chemists would describe this difference in reactivity as an example of

Chemoselectivity

Explanation:

Chemoselectivity is a term that refers to the preferred result of a chemical reaction between two different functional groups.

In this case, the chemical reaction would be the bromination, which is preferred (or chemoselective) towards non-aromatic alkene groups, compared to aromatic alkene groups.

the correct answer is a

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation: