From the words lettered A to D, choose the word that best completes each of the following sentences. ............to school, it began to rain heavily.

From the words lettered A to D, choose the word that best completes each of the following sentences.
............to school, it began to rain heavily.

Answer Details

The best word to complete the sentence is "As I was walking". This is because it indicates the time when the rain started and shows a connection between the two events, i.e., starting to walk to school and the heavy rain.