Q.Find the odd one:

C2C (Consumer-to-Consumer) e-commerce covers transactions carried out between one consumer and another, usually with the help of a third-party online platform.

E-commerce is classified by who is buying and who is selling. The three options here are:

• B2B (Business-to-Business) — trade between two business firms, e.g. a manufacturer selling raw material to a wholesaler.
• B2C (Business-to-Consumer) — a business selling goods or services directly to the final consumer, e.g. an online retail store.
• C2C (Consumer-to-Consumer) — one consumer selling to another consumer, generally through an intermediary website that provides the platform, listing and payment facility. Examples include online auction sites and second-hand goods marketplaces where individuals list items for other individuals to buy. …

The odd one out is A to Z. The others are genuine categories of e-commerce, whereas 'A to Z' is not a recognised type.

E-commerce is classified according to the parties involved in the online transaction:

• B to B (Business to Business) — trade between two businesses, e.g. a manufacturer selling to a wholesaler.
• B to C (Business to Consumer) — a business selling directly to individual consumers, e.g. an online shopping site.
• C to C (Consumer to Consumer) — one consumer selling to another, usually through an online platform such as a re-sale website. …