An organism that has adapted to surviving in both salt water and fresh water would be best suited to survive in which aquatic ecosystem ?
A.) the intertidal zone
B.) a river
C.) an estuary
D.) the open ocean

Option C, Estuary

Explanation:

An estuary is a geographical entity where the salty water of ocean mixes with fresh water of river. The resulting water is known as brackish water. The brackish water is not as salty as that of ocean and also the salinity level of water rise and fall regularly.

Thus, an organism that is able to live in both salty water and fresh water environment can survive in an estuary.

Hence, option C is correct

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.  

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )