Dollar-unit-sampling is a method of selecting invoices for audit where the probability of selection is proportional to the dollar value of the invoice. Suppose that an auditor has 120 invoices for a total dollar value of $123,000. The total dollar value of 75 small-valued invoices is $10,000. The auditor picks an invoice for audit by randomly picking $1 and finding the invoice to which it belongs. What is the probability that a small-valued invoice will be selected?a) 10,000/123,000.b) 75/120.c) 75/10,000.d) 1/75.