For 100 Points! Which of the following factors are responsible for the annual rise and fall in carbon dioxide levels? (Several choices may be correct.)

A) fallen leaves decaying in autumn
B) consumption of more fossil fuels in the winter
C) plant growth in the spring
D) increase in surface temperature of the earth during summer

PS: I've tried A & D and B & D (they were both wrong)

I believe the answer is

A & C.

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.  

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.