A cylinder containing an ideal gas is in a vertical position and has a piston of mass \(M\) that is able to move up or down without friction (figure). If the temperature is increased,
                     

1. both \(P\) and \(V\) of the gas will change.
2. only \(P\) will increase according to Charles' law.
3. \(V\) will change but not \(P.\)
4. \(P\) will change but not \(V.\)