Directions: Complete the following MCQ using an appropriate preposition.
I like walking alone on the streets ________ night.

The correct answer is: At

The correct answer is "at".
We use the preposition "at" to indicate certain time segments within a day, namely dawn, dusk, noon and night. Here, the speaker is talking about his preference of walking alone in the streets during a specific time of the day, that is, night. So, the correct answer is "at".