For this type of game, it is very important that we diagram our out-group as well as our in-group.
Consider your first rule about Q and R. There can only be one leader, so Q and R cannot both be on the project. Q ---> not R R ---> not Q This is why I have reserved a spot in the out-group for either Q or R.
We are told that Taylor is not a project member. Based on our second rule, we can also conclude that S will not be a project member.
In: _ _ _ Out: S T Q/R _
The question asks us who must be a project member. But, because our outgroup is nearly full, it helps to think, who cannot be out?
The remaining workers: Q/R, V, W, X
What happens if X is out? That leaves Q, R, V and W. There is no combination of 3 workers from this group that will work. Q and R cannot coexist, W cannot coexist with R and V. This is why X has to be included.