If both Ruiz and Tapia examine G, which one of the following technicians must examine F?

Im confused because if both R and T are in G, then that means that S cannot go into F because it would trigger X going into G as well, which is not possible. With that being said, the only two possible answers left that could go into F are X & W. The way I see it, both X & W MUST go into F because there are no other options left, as you cannot put S, R, or T into F. Can someone please elaborate on how one MUST go into F because the way I see it, X & W MUST go into F.