What about 18?

[muon2]

Nowhere does the passage mention belts. This causes confusion with the question.

Perhaps the question's use of belts means the shoulder straps, in which case Beesley's logic is correct to choose D. However, when I shop for a backpack (and I just did last month), the belt is the extra support that goes around one's torso, not the shoulder straps. If the question's use of belts meant this and not the shoulder straps then answer A wasn't discussed at all. In fact the passage doesn't even mention straps, just design for shoulder support.

I would not use this question to test English reading comprehension.

[muon2]

What abou 44?

I believe C (d-c-b-a) is the best answer. d and c are fairly clear from the dates given. b is happening now, but a is only proposed to happen. If a happens it is in the future. That puts a last.