Answer:
Water pollution can put negative C. effects on our health.
Step-by-step explanation:
A is wrong because all types of contamination are bad. (Otherwise, it wouldn't be contamination.)
D. is wrong because if a problem isn't negative, then it isn't a problem.
B. is wrong because affect is a verb, and it means to produce an EFFECT. An effect is a noun, and therefore C is the correct answer.