Mercury Pollution may be caused due to which of the following?

1. Coal based thermal power plants.
2. Exhausts from supersonic jets.
3. Automobiles exhaust
4. Thermal waste incinerators

Select the correct answer using the codes given below.
a) 1, 2 and 3 only
b) 1, 3 and 4 only
c) 1 and 3 only
d) 1 and 4 only

Ans-[B] 

Explanation– Artificial sources include – Alkali and metal processing, incineration of coal(in power plants too), medical waste and waste incinerators, electrical/electronics devices, automobiles exhaust and mining of gold and mercury. Natural sources of mercury pollution are volcanoes, geologic deposits of mercury and volatilization from the ocean. Often some springs are naturally high in mercury concentration.