. . . . . . . . off the light, I went to bed. A. Switched B. Before C. Switching D. Having switched

The correct answer is: D. Having switched

The other options are:

• A. Switched – This is incorrect because the sentence is in the past tense, so the verb should also be in the past tense.
• B. Before – This is incorrect because it does not make sense to say “Before I went to bed, I went to bed.”
• C. Switching – This is incorrect because it does not make sense to say “Switching off the light, I went to bed.”

The sentence “Having switched off the light, I went to bed” means that the speaker turned off the light before going to bed. This is the most logical and grammatically correct interpretation of the sentence.