The answer key for q18 says that R must be performed sixth (answer D), but I am convinced that R must be performed seventh (answer E). It states that "If exactly two compositions are performed after F but before O (F_ _ O), then R must be performed"... and so on. Why wouldn't the following compositions work where R must be performed seventh, as opposed to sixth:
P F S H O T R L
Here, TR are together, F is at least two compositions before R, P is before S, S is at least one composition before O, O is in the fifth spot, and L is in the last spot. With that said, I am confused why my answer is wrong, according to the answer key.