Question

the oceans dead zones
most dead zones are created when oceans have too much nitrogen and phosphorus. these nutrients are in the plant food, called fertilizer, used on farms and in gardens. heavy rains cause these nutrients to flow downstream into the ocean. then, algae, which are tiny plant - like organisms, grow quickly near the ocean surface and block sunlight from getting to the bottom of the ocean. sunlight is needed to increase the amount of oxygen in the water. if there is not enough oxygen in the water, plants and ocean animals can die.
what can cause a dead zone to form?
select one:
farmers grow algae that flow into the ocean when it rains.
fish eat too much algae.
plant food is washed into the ocean.
clouds keep sunlight from getting to the bottom of the ocean.

Explanation:

The text states that dead zones are created when oceans have too much nitrogen and phosphorus (from plant food/fertilizer). Heavy rains wash these nutrients (plant food) into the ocean. Algae grow, block sunlight (which is needed for oxygen production). Lack of oxygen kills plants and animals. The option "Plant food is washed into the ocean" directly aligns with the cause described in the text.

Answer:

Plant food is washed into the ocean.