To answer this question, we need to understand the correct preposition to use when referring to being in bed at a specific time.
Option A) "at bed" - This option is incorrect because we do not use the preposition "at" before the word "bed" in this context.
Option B) "in bed" - This option is correct. We use the preposition "in" before the word "bed" to indicate being inside the bed.
Option C) "on bed" - This option is incorrect because we do not use the preposition "on" before the word "bed" in this context.
Option D) "none of these" - This option is incorrect. The correct answer is option B.
The correct answer is B) "in." This option is correct because we say "I am in bed by eleven o'clock in the evening" to indicate being inside the bed at a specific time.