Why is water vital to maintaining a constant internal environment?
a. it is cohesive
b. it is adhesive
c. it is a good solvent
d. it has a high specific heat

It is a good solvent.

Explanation:

Water plays an important role in the physiological processes of our body. The human body has 60%-65% of water. It is present in different cells of the body and maintains the osmosis. Osmosis is the water balance which is maintained by antidiuretic hormone/ ADH. This hormone releases from the pituitary gland. When there is less water content in the body, the secretion of ADH is more. This helps in reabsorption of water in the nephrons and checks less water content. When the water is excess in the body, the ADH will release in less amount and helps in excretion of more water by the kidney. Thus a water balance can be kept in the body.  

Water also helps in maintaining constant body temperature. When the body gets heated, it starts sweating and the evaporation of sweats cools down the body.  

Water is necessary for various cellular reactions and expels out the toxic materials from the body. In this way, water maintains a constant internal environment.

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.