Which of the following statement(s) is (are) incorrect reason for eutrophication?
(A) excess usage of fertilisers
(B) excess usage of detergents
(C) dense plant population in water bodies
(D) lack of nutrients in water bodies that prevent plant growth
Choose the most appropriate answer from the options given below:

The question asks which statement is an incorrect reason for eutrophication. Eutrophication is the excessive enrichment of water bodies with nutrients (especially nitrogen and phosphorus), which triggers rapid algal and plant growth, oxygen depletion, and ecosystem damage.

(A) Excess usage of fertilisers causes nutrient runoff (nitrogen and phosphorus compounds) into rivers and lakes, directly contributing to eutrophication. This is a correct reason.

(B) Excess usage of detergents introduces phosphates into water bodies, which promotes excessive algal growth. This is a correct reason for eutrophication.

(C) Dense plant population in water bodies is directly linked to excess nutrients already present, and such overgrowth further depletes oxygen, worsening eutrophication. This is a valid reason associated with the eutrophication process.

(D) Lack of nutrients in water bodies that prevent plant growth is the exact opposite of what causes eutrophication. Eutrophication occurs due to an excess of nutrients. A nutrient deficiency leads to oligotrophic (nutrient-poor) conditions, not eutrophication. This is clearly an incorrect reason.

Therefore, the incorrect reason for eutrophication is (D) only.