Question

Select a suitable conjunction to complete the sentence:

He was walking back home _____ he heard the explosion.

• A. as
  
• B. if
  
• C. when
• D. that

Answer 1

The correct option is C when

'As' is a conjunction which indicates reason.
'If' is a conjunction which indicates condition.
'When' is a conjunction which indicates time.
'That' is a conjunction which indicates reference to something.
The given sentence is time-related and, therefore, the correct option is:
C) when.