What would be the most effective way for him to encourage repeat business?

Mark is the owner of a portal storefront that sells gaming software. What would be the most effective way for him to encourage repeat business?

A.
Allow new customers a 10 percent discount on their first order.

B.
Provide a FAQ page and knowledge base for each game.

C.
Offer discounts on game accessories during the checkout process.

D.
Use up-selling techniques to sell more advanced games.