Correct answer is (a) Enhanced biological phosphorus removal
Easy explanation: Enhanced biological phosphorus removal, also known as EBPR is a method for removing phosphate in activated sludge system. This system is aided by anaerobic tank which is the main element in the system and therefore, it helps in effective phosphorus removal. Enhanced bacterial phosphorus removal is not the term, though biological organisms are used. Also, reduced biological phosphorus removal is not the term used. Enhanced biological magnesium removal is not used to remove phosphate.