The correct answer is: D. None of these
An optional voucher is a type of voucher that can be used for a variety of purposes, such as purchasing goods or services, making donations, or redeeming for cash. It is not a type of conventional or unconventional voucher.
A conventional voucher is a type of voucher that is typically used for a specific purpose, such as purchasing a gift card or redeeming for a discount on a purchase. An unconventional voucher is a type of
voucher that is not typically used for a specific purpose, such as a gift card that can be used for any purchase or a voucher that can be redeemed for cash.Optional vouchers are more flexible than conventional or unconventional vouchers because they can be used for a variety of purposes. This makes them a good option for people who want to have the flexibility to use their vouchers for whatever they need.