We are asked to identify the variable that CANNOT be fifth. This means any variable that can be placed fifth would be eliminated. Therefore, we are looking to determine if the variable G could be fifth, not if it must be fifth.
Our rules do not tell us that any specific variables must precede G. However, the rules do tell us that G must precede K (Rule #1) and that K must precede M (Rule #3). Therefore, there are only two specific variables (K and M) that G must precede. This allows us to place G in the fifth spot without breaking any rules. An example of a valid arrangement in which G is placed fifth is: LPHJGKTM.
In your post, you point out that P, H, and L can go at the beginning of our sequence. Since we have H and L, we can place J immediately afterwards (Rule #2). This allows us to fill the first four spots before placing G fifth. We could also place T in an earlier spot, as its only restriction is being placed sometime before M.
M is the correct answer because our rules tell us that M has a total of five variables that must precede it (L, P, G, K, and T). Therefore, the earliest that M could be is sixth, making it impossible for M to be fifth.
Does that make sense? Please let us know if you have any other questions and best of luck with your studies!
