Q.

Biological magnification is defined as:

1 the accumulation of harmful chemicals at each trophic level of the food chain.  
2 the accumulation of organic matter at the first trophic level of the food chain.  
3 the reduction of energy at each trophic level of the food chain.  
4 an increase in the population of a species at each trophic level of the food chain.  

Ans.

(1)

The accumulation of harmful chemicals at each trophic level is called biological magnification.