Question

question 4
aquatic animals such as fish and frogs are especially good indicators of water pollution because _.
most chemicals are water soluble so they enter these organisms through drinking or skin absorption
these organisms are the most abundant on earth
the metabolism of these organisms is most like ours
they are easy to catch
all chemical toxicants are found in water

Explanation:

Aquatic animals like fish and frogs live in water. Water - soluble chemicals can enter their bodies either when they drink water or through their skin (since their skin is permeable in an aquatic environment). This makes them good indicators of water pollution as they are directly exposed to water - borne contaminants in these ways.
The second option “these organisms are the most abundant on Earth” is incorrect because abundance alone doesn't make them good pollution indicators. The third option “the metabolism of these organisms is most like ours” is not relevant to their role as water - pollution indicators. The fourth option “they are easy to catch” is a practical aspect but not the scientific reason for their use as pollution indicators. The fifth option “all chemical toxicants are found in water” is false as some toxicants can be in air or soil too.

Answer:

most chemicals are water soluble so they enter these organisms through drinking or skin absorption