Question

an algal bloom can be caused by an abundance of a certain nutrient. what nutrient can cause an algal bloom? oxygen phosphorus copper carbon

Explanation:

Algal blooms are often caused by excessive nutrients like phosphorus (and nitrogen) in water bodies, which promote rapid algae growth. Oxygen is a gas needed by organisms, copper is a metal (not a primary algal - bloom - causing nutrient in typical cases), and carbon in the form relevant here (e.g., carbon dioxide) is not the main nutrient for algal blooms in the context of this question. Phosphorus runoff (from fertilizers, etc.) into water bodies is a common cause of algal blooms.

Answer:

B. phosphorus