Answer :

To determine which of the provided adjectives best defines an "interlude," let's understand the meaning of each word and the context of "interlude."

An interlude typically refers to an intervening period or a pause between events, often providing a break from more serious or intense content.

Here are the given adjectives and their definitions:
- Spiritual: relating to religious matters or the human spirit.
- Instructive: intended or likely to teach something.
- Witty: showing or characterized by quick and inventive verbal humor.
- Bawdy: dealing with sexual matters in a comical way.
- Somber: dark or dull in color or tone; gloomy.

Considering these definitions:
1. Spiritual typically relates to religion or the soul and does not commonly describe the nature of an interlude.
2. Instructive suggests that the interlude aims to educate, which is not its typical purpose.
3. Witty tends to describe humor but does not fully capture the essence of an interlude.
4. Bawdy deals with humor, often sexual, and can describe interludes that provide a comic break.
5. Somber describes a serious or gloomy tone, which is less likely to characterize an interlude.

Given the context of an interlude providing a lighter or comic break, the adjective "bawdy" is the most appropriate choice.

Therefore, the best adjective that defines an interlude from the provided options is:

○ D. bawdy