Short answer: All four animals listed can be sold in many contexts, but in common practice camels are far less frequently sold than horses, dogs, or cats, so “a camel” is the option least typically found for sale. This aligns with general observations that horses, dogs, and cats are widely bought and sold or adopted, while camels are comparatively rarer in many markets and typically traded in specialized settings or regions. Details

• Horse: Frequently bought and sold through breeders, auctions, and private sales. Availability and market activity vary by region and breed.

• Dog: Widely sold or adopted across shelters, breeders, and pet stores; high volume compared to other listed animals.

• Cat: Commonly sold or adopted via breeders and shelters; very broad market presence.

• Camel: Much less common in general retail markets; often found in specialized markets, specific regions, or agricultural settings.

If you’d like, I can tailor this to a particular country or market (for example, the U.S., the U.K., or a Middle Eastern region) and provide more precise notes on availability and typical sale channels.