Answer: The correct answer is –

D. 3,2,1,5,6,4

Explanation:

Infection of HIV (human immuno deficiency virus) into the host cell primarily involves the following steps-

1) Binding of virus to host cell,

2) Fusion of viral coat to host cell membrane so that entry of virus takes place.

3) Action of reverse transcriptase enzyme to make viral DNA from viral RNA,

4) Integration of viral DNA into host genome,

5) Replication of viral genome along with host genome.

6) Assembly of viral particles through viral mRNA (formed through transcription).

7) Budding of new viral particles from the membrane.

According to this sequence, option D) is the right answer.