Why did metics not have the full rights of citizens?

A.
They were artisans.

B.
They were aristocrats.

C.
They were merchants.

D.
They were foreigners.

D. They were foreigners.

The reason metics did not have the full rights of citizens is because they were foreigners. To reach this conclusion, one needs to understand the term "metics." In ancient Greece, metics were free non-citizens who resided in a city-state but were not native-born or granted citizenship. They were typically foreign merchants, artisans, or workers who lived in Greece but did not have the rights and privileges of a citizen. Therefore, option D - "They were foreigners" - is the correct answer.

The correct answer is D. They were foreigners.