How is a merchant defined in the context of PCI DSS?

In the context of PCI DSS, a merchant is specifically defined as an entity that accepts payment cards for goods or services. This definition is crucial because PCI DSS compliance focuses on protecting cardholder data during transactions, which occurs when merchants accept payment cards, whether in-person, online, or via other means.

This definition helps delineate the responsibilities and obligations that merchants have in ensuring the security of cardholder data and maintaining compliance with PCI standards. Merchants come in various sizes, from small businesses to large retailers, but their common role is the acceptance of payment cards in exchange for products or services, which places them at the center of potential data risks that PCI DSS aims to mitigate.

The other options do not accurately capture the specific role of merchants in the transaction process. While entities that issue payment cards or those involved in financial services do play critical roles in the payment ecosystem, they do not fit the specific definition of a merchant under PCI DSS. Option D, which mentions any entity processing payment transactions, is broader and could include payment processors and gateways, thus deviating from the specific focus on those entities that directly accept payment cards in exchange for tangible or intangible goods or services.