If the act is a lawful one and not a criminal act and if in the course of such act any one of the person's jointly doing that act commits an offence, then
1
All the persons shall be liable under Section 34 of I.P.C.
2
only the doer of the act shall be liable for it and not others and Section 34 of I.P.C. shall not apply.
3
Nobody shall be liable for it and not others and Section 34 of I.P.C. shall not apply.
4
No other person except the real doer of the act shall be liable for it.