Select the most appropriate meaning of the given Idiom: "Donkey’s year"

A very long time

The most appropriate meaning of the idiom "donkey's year" is a very long time. This idiom comes from the literal meaning of the phrase, which is that a donkey's gestation period is 11 months, which is considered to be a long time for a mammal. However, the phrase came to be used figuratively to describe a very long period of time.

For example, if you say that something will take "a donkey's year," you mean that it will take a very long time. Or, if you say that you have been waiting "a donkey's year" for something, you mean that you have been waiting a very long time.