The given graph shows changes in three components X, Y and Z in a water body after point P(where fertiliser run off from crop field took place).
Select the correct statement regarding X, Y and Z.

Options

A. X could be phosphate compounds whose concentration gradually reduced downstream due to their consumption by growing aquatic plants.
B. Y could be nitrate compounds which initially increased due to introduction of NPK fertilisers whereas Z represents decomposer microbes whose number increased in order to decompose these compounds.
C. Y could be algae which multiplied rapidly due to nutrient enrichment of water body whereas X could be dissolved oxygen which started reducing simultaneously with the increase in decomposition activity of microbes Z after death of algae.
D. Y could be aquatic animals which initially increased in number due to consumption of large amount of aquatic plants X and then decreased gradually with the reduction in plant population.

Answer

C