Which one of the following could be the schedule of advertisements?

I understand that H needs to come in the week preceding J, however because there can be one variable that is in two weeks, why can't it be 1: H K 2:H J 3:G O 4:L M Once again, I understand that J cannot exist without H coming in the week preceding it, however, it does not state H cannot exist without being in the week preceding J or can only exist in the week preceding J. I am perplexed by this and hope to have a valid answer so I do not make the same mistake on the real LSAT.