Due to improper / indiscriminate disposal of old and used computers or their parts, which of the following are released into the environment as e-waste?

1. Beryllium
2. Cadmium
3. Chromium
4. Heptachlor
5. Mercury
6. Lead
7. Plutonium

Select the correct answer using the codes given below.
a) 1, 3, 4, 6 and 7 only
b) 1, 2, 3, 5 and 6 only
c) 2, 4, 5 and 7 only
d) 1, 2, 3, 4, 5, 6 and 7

Ans-[B] 

Explanation- Heptachlor is an organochlorine compound that was once used as an insecticide. Plutonium is a radioactive material used in the nuclear reactors and bombs. Leaving these two all other are commonly used elements in the electronic circuits of computers.