He and Mina went in and took a seat at a table, setting down the grocery bag in an empty chair. They ordered tea, and Uncle Moti sighed happily. What does the idiom “took a seat” mean?

B. Sat down.

Explanation:

Idioms are words, groups of words used to refer to mean something that is not deducible from the given words. It gives a metaphorical meaning of what is intended.

In the given passage from "The New Village", the idiom "took a seat" means Uncle Moti and Mina sat down at the tea shop. The phrase "took a seat" does not mean to literally carry or take a seat but it refers to sitting, the act of sitting one down.

Thus, the correct answer is option B.