Some states bordering the Gulf of Mexico experienced a drought, or period of time with very little rainfall, in 2012. Scientists think the drought affected the size of a dead zone in the gulf waters. Dead zones develop when large amounts of fertilizers from the surrounding land get washed into the gulf when it rains. The fertilizer causes algae to grow in the water. When the algae die, they sink to the bottom. They use up oxygen as they decay. Then the water does not have enough oxygen left for fish to live. The area becomes a dead zone. During the drought of 2012, however, the dead zone became smaller.
According to the article, what is the most likely reason a dead zone in the Gulf of Mexico became smaller in 2012?
1. More algae grew in the water.
2. Less fertilizer washed into the water.
3. Less oxygen was left for fish in the water.
4. More algae sank to the bottom of the water.