I fell like "D" is could be true, not must be true.

@Adam-Estacio, Happy to help. From the stimulus, we know that we have two types of mail. 1) correctly addressed mail 2) incorrectly addressed mail We know that correctly addressed mail always arrives on time unless it's damaged. For incorrectly address mail, we don't know anything. We're also told that most mail arrives late. That's odd. This means that most mail either is incorrectly addressed or it's correctly addressed and damaged. However, we also know from the stimulus that at most only a few of the correctly addressed mail is late. We know this because we're told in the first sentence that "Nearly all mail that is correctly addressed arrives at its destination within two business days of being sent." This means that it must be the case that there is a lot of mail that's incorrectly addressed. The question asks, "If the statements above are true, which one of the following must be true?" (A) says, "A large proportion of the mail that is correctly addressed is damaged in transit." You were thinking that this could be true. The problem with (A) is that it contradicts the first sentence, as we're told that nearly all mail that's correctly addressed arrives at its destination within two business days. If this is true, then it certainly doesn't have to be true that a large proportion of the mail that is correctly addressed is damaged in transit, as we know a minority of this mail is damaged. (D) says, "A large proportion of mail is incorrectly addressed." (D) has to be true because we know that most mail arrives late, and we also know that most correctly addressed mail arrives at its destination on time. This means that in order for most of ALL mail to be late, a very large fraction of all mail has to be incorrectly addressed. Does this make sense? Let us know if you have any more questions!