How many of the following statements about  water pollution are true?

(a) Thermal waste waters change the species composition of the water bodies.

(b) Waste water from industries often contain toxic substances, notably, heavy metals.

(c) Algal blooms cause deterioration of the water quality and fish mortality.

(d) The prime contaminants in agricultural wastes are plant nutrients.

Agricultural wastes consists of contaminants like nitrates and phosphates, which act as plant nutrients. 

Thermal wastewater eliminates or reduces the number of organisms sensitive to high temperature, and may enhance the growth of plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and fauna. Thus, change the species composition.

Algal blooms cause deterioration of the water quality and fish mortality. Some bloom-forming algae are extremely toxic to human beings and animals.

Waste water from industries like petroleum, paper manufacturing, metal extraction and processing, chemical manufacturing, etc., often contain toxic substances, notably, heavy metals (defined as elements with density > 5 g/cm³ such as mercury, cadmium, copper, lead, etc.) and a variety of organic compounds.