Your correct on everything
he is pondering suicide and what comes after death i hope this helped! :)
The answer is who because is makes it makes the most sense
It might be said that the adjective phrase to complete this sentences is option B (across the street) because it is providing information about the apartment, it is modifying the noun. In other cases, they provide more information, "because" is used to give a reason so it would be considered adverbial as well as, "for five years", it is related to time. Option D could be understood as a complement of the noun but not a modifier.