A man of mass m is on the floor of a lift. The lift moving up with acceleration ‘a’, then 

a) the net unbalanced force on him is 'ma' 

b) the normal reaction exerted by the floor on the man is m(g + a) 

c) the apparent weight is greater than his true weight

As the body is moving up with an acceleration of 'a'.

according to second law of motion we can conclude that there is a unbalanced force acting on the particle responsible for acceleration.

F=ma.

As the normal reaction needs to balance impart acceleration overcoming the gravitational force.

Normal force is given by N=m(g+a), so the apparent weight is more than the true weight of person.