If there were 1000 sheets of paper, then the thickness of each sheet would be 1.875 in divided by 1000.
1.875/1000 = 0.001875
Since there are 500 sheets of paper, each one is twice as thick as 0.001875, so each sheet is 0.00375 inches thick. 0.015 is much greater than 0.00375, so it must be incorrect.
The first option is cheaper if that’s what you’re asking. It’s cheaper because it has a smaller slope so overall will have a lower price than the other option.