Please help

From our initial setup, we can tell that 5 must be a t, since it cannot be r or s, and that 8 must be a t, because it can't be another s, and putting an r there would violate the r/t rule. So our initial setup is _ R T _ _ _ S T However here, we are given the condition that there are two rs facing each other. The only two that could fit this bill are. 3 and 5, so we have _ R T _ _ R S T We also know that since we must have a T next to every R, spot 2 must be a T. This eliminates every option but b

Sorry, spot 2 must be T, which eliminates everything but b.m