A. Phosphorus
Over 44 years, Dr. Schindler and his team tested the effects of phosphorous, nitrogen, and carbon on algae growth. Their research showed that phosphorus, and not carbon or nitrogen, increases algae growth in aquatic ecosystems.
The answer is D. An irritant that because embedded in the mantle
An element is also a pure substance. The reason for this is because an element contains only one type of particle.
Option A is correct