With respect to Computer Virus, which one of the following statements is True?
1
It is a kind of physical impurity which when present in the CPU causes it to malfunction.
2
It is a computer program that infects a computer and thereby sends unsolicited bulk email.
3
It is a computer program which copies itself to infect a computer without the permission/knowledge of the user.
4
It is an accumulation of dust on the hard disk causing it to malfunction.