With regards to the trade credit term, $2/10$ net $30,$ why should business customers pay invoices with this trade credit term within ten calendar days?

Question $4$ options:

Doing so enables them to take advantage of discounts, which is about $2\%$ in interest per year.

Doing so enables them to take advantage of discounts, which is about $37\%$ in interest per year.

Doing so enables them to take advantage of discounts, which is about $24\%$ in interest per year.

Doing so enables them to take a $20\%$ discount from the net amount of the invoice if they pay within $30$ days.