An organism's "trophic level" refers to . See Concept 54.2 (Page 1221)
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the rate at which it uses energy
the intensity of its competition with other species
its food source
whether it is early or late in ecological succession
where it lives

covalent bonding is a form of chemical bonding between two non metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds.

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.

i believe your answer would be c.. : )