This is interesting. Let me think.
>Albert says "I don't know which is the correct pad, but I know that you don't either."
>Bernard tells him "At first I didn't know which was the correct pad, but now I do."
>Albert then replies "Now I know which is the correct pad too."
This leads me to two conclusions:
>The points have to do with what each henchman said.
>The points do not have to do with what the henchmen told each other.
I also believe that the number of people in the trolley doesn't have to do with the pad in question.
If the points do have to do with each henchman:
>Albert knows the letter.
>Bernard has the number and Albert tells him the letter.
>Albert now also knows both.
Which would mean that Albert stated something about either which letter or which pad. And Bernard stated something about his number or the pad too.
It can't be a number with just one pad because Bernard would know immediately. That narrows it down to rails 1, 2, 3 and 4.
It also can't be on A or B, because those are the letters that B5 and A6 are on.
Thus, you can narrow it down to just lines C and D and it imagine it as just those two rails.
This means that, because Bernard knows the number and letter, it can't be 1, which leaves you with two options.
Therefore, the answer is D2, C3 or D4. We can apply the "two option elimination" again, and because D leaves you with two options, making the problem again unsolvable, that means that it can't be line D.
The answer is C3.
If the answer does not have to do with Albert and Bernard:
Cheryl is lying about planning to kill 50 people, and made the problem so that you will kill 20 people for her.
This was really interesting to think through. Thanks, anon.