Prom/Promotion price refers to ( ).

A、a product, service, or programme that is offered at reduced prices or rates.
B、a product, service or programme that is offered at a 30% discount to consumers.
C、a product or service that is offered at a lower price than regular price during the promotion.
D、a product or service that is offered to consumers at a regular price while the second one is offered to them for free.