It so happens that ______
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. when.
- How- it is used to show manner.
- If- It is used to show condition.
- When- it is used to show time.
- Why- it is used to show the reason.
As there is a verb "happen" before the blank space it gives the sense of time.
Hence, "when" will be the correct choice as the answer.