"Net 30" is a common business term that is shorthand for the fact that the seller or provider of services expects to receive full payment of the total invoice amount no more than 30 calendar days after the item has been shipped or the service has been rendered.
Because cash flow is considered to be the "life blood" of any business, and also because the older an invoice is, the less likely it is to be paid in full, it is a common business practice to provide customers an incentive to pay more quickly by giving them a discount if they do so, typically by offering a percentage off the invoice amount.
In you question the percentage discount is 8%. 8% of the invoice amount is:
.08 x 1750 = 140.
So $140 is your discount for payment in 15 days.
1750 - 140= 1610
Therefore choice A is correct.