She asked her little boy why, he replied that he didn't know and it was just what?\nOptions:\n- case\n- reason\n- how\n- because\n- answer
Let’s work this out in a step by step way to be sure we have the right answer.
because
She asked her little boy why, he replied that he didn't know and it was just because.

Reply of 'why' should be 'because of'.

.

The answer: because