Study the geologic time scale. A geologice time scale. 4,600 M Y A to 544 M Y A, Precambrian Time. 544 M Y A to 250 M Y A, Paleozoic Era. 250 M Y A to 65 M Y A, Mesozoic Era. 65 M Y A to Today, Cenozoic Era.

The Eocene period exists in Earth’s history around 34 MYA.

What could a scientist do to determine what era the Eocene period belongs to on the geologic time scale?

learn what happened during Precambrian time
study information related to the Cenozoic era
view the timing of events in the Mesozoic era
research events that happened during the Paleozoic era

i don't know, but does anyone wanna be friends? i'm doing my homework at 1: 49 in the morning : /

d. planting trees

the trees take in carbon to make oxygen.

the right option is; decreased genetic variation  

decreased genetic variation describes the effect of this environmental change.

genetic variation is the naturally occurring genetic diversities or differences between organisms of the same species in a population. genetic variation allows the survival and adaptability of a species when they encounter changing environmental conditions. when an endangered species reduces, it loses genetic variation which may not be restored even if the species rebound and will only be recovered through the gradual collection of mutations over many years.