Question

how can agriculture contribute to water pollution?
reduced algal blooms
pesticide and fertilizer runoff
too little irrigation
planting monocultures

Explanation:

Agriculture can contribute to water pollution through pesticide and fertilizer runoff. When these chemicals are washed away by rain or irrigation, they enter water bodies. Pesticides can harm aquatic life directly, while fertilizers (high in nutrients like nitrogen and phosphorus) can cause excessive growth of algae (algal blooms when not reduced). Algal blooms deplete oxygen in water, harming fish and other organisms. Planting monocultures (a single crop type) can lead to soil degradation and increased runoff potential as it reduces soil cover and biodiversity that helps absorb water. Too little irrigation is more related to crop yield issues rather than direct water pollution in the context of typical agricultural - water pollution links.

Answer:

pesticide and fertilizer runoff