Question

A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this.

(i) Lots of urea and phosphate fertilizer were used in the crops in the vicinity 

(ii) The area was sprayed with DDT by an aircraft 

(iii) The lake water turned green and stinky 

(iv) Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis. 

(a) (i) and (iii) 

(b) (i), (ii) and (iv) 

(c) (iii) and (iv) 

(d) (ii), (iii) and (iv)

Answer 1

Correct option: (a) (i) and (iii)

Explanation:

Lots of urea and phosphate fertilizer were used in the crops in the vicinity and the lake water turned green and stinky. Due to this, lake near a village suffered heavy mortality of fishes within a few days.