An organ within an organism accomplishes tasks. To engage in these tasks, an organ typically requires energy provided by other organisms.
B
interaction with other organ systems.
С
communication with other organisms.
D
segregation from other organ systems.

I think that it is the first one :)

Explanation:

Pls pls tell me if  im wrong, ill do my best to fix it

explanation:

on disadvantage of hydroelectric power is the cost. another disadvantage of using hydroelectric power is finding a water source powerful enough to harvest hydroelectric power.

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.