The person weighs 600N and wants to sit in the hanging basket and pull it up at a constant speed with the pulley block, as shown below. Given that the hanging basket weighs 240N, regardless of the pulley weight, then the force he uses should be People and hanging baskets are regarded as a whole,

∵ Lifting the hanging basket at a constant speed,

∴3F=G hanging basket +G people =240N+600N=840N.

∴ People pull:

F= 13×840N=280N。

So choose a.