Explanation:

Option 1, stopping the water cycle, is not a plausible outcome. The water cycle is a natural process that entails evaporation, condensation, and precipitation, and it can`t be stopped by pollution.

Option 2, preventing precipitation, is also not likely. While pollution can influence the amount and acidity of rain to some extent, it would not be able to halt precipitation completely.

Option 3 is the correct answer. Water pollution can indeed make oxygen molecules unavailable to water plants. Aquatic plants rely on dissolved oxygen in the water for survival. If the water is polluted, particularly with substances that induce excessive growth of certain microorganisms, available oxygen can become exhausted - a scenario known as hypoxia. This can lead to the death of aquatic plants and animals.

Option 4 is not accurate. Nitrate is often a component of water pollution, not something that pollution makes unavailable to plants. Excess nitrate can actually cause excessive growth of algae and other plants, leading indirectly to hypoxia.