A key factor in a voucher system includes all of the following except:

a. Only approved departments and individuals are authorized to incur a liability that will result in the payment of cash.
b. Procedures for purchasing, receiving, and paying for merchandise are divided among several departments.
c. The system limits the individuals that can incur cash payment liabilities for a company.
d. It is applied to purchases of merchandise inventory and all other expenses.
e. It is not necessary if the supplier provides both receiving report and invoice with the merchandise shipped.