Answer:
Hello! The correct answer should be "Excess phosphorus from the runoff of fertilizer and animal waste that ends up in ponds."
Step-by-step explanation:
An algal bloom is mostly caused by the presence of large amounts of nitrogen and phosphorus present in water. These nutrients are washed away from lands and farms that are heavily riddled with nitrogenous and phosphatic fertilizers.
Rain acts as an agent by washing these leachable nutrients from the soil into water bodies such as rivers and streams, which eventually end up in large reservoirs such as lakes and oceans.
These nutrients are also deposited into waterways through drainage systems. Due to poor sewage treatment, untreated raw sewage finds its ways into water bodies, and because it is rich in nitrogen compounds such as nitrates and ammonia, it causes algal bloom.
Water pollution, particularly the discharge of poorly treated or untreated industrial waste into waterways, leads to the release of raw toxic waste into water systems. Since it contains nutrients and compounds such as nitrogen, lead, and phosphorus, the outcome is the dense growth of algae.