Question

whitney, tania, and arissa go swimming in a lake. whitney breaks into a rash while her friends do not. water quality tests show toxins in the lake. whitney is the only one that uses skin medication. which statement best explains why whitney got a rash from the water, but her friends did not?
whitneys medication has a combined relationship with the toxin in the water.
whitneys friends have better immune systems to avoid illness than she does.
whitneys reaction is chronic and is unlikely affected by the environment.
whitneys medication has a cancelling relationship with the toxin in the water.

Explanation:

Whitney is the only one with skin - medication among the three. Since she got a rash and there are toxins in the water, it's likely the medication interacted with the toxin to cause the rash. Other options lack sufficient evidence from the given information.

Answer:

Whitney's medication has a combined relationship with the toxin in the water.