Sentence Correction - Verbal and Reasoning

Directions to SolveWhich of phrases given below each sentence should replace the phrase printed inboldtype to make the grammatically correct? If the sentence is correct as it is, mark 'E' as the answer.
Q1:

What happens to all those travellers on the ship was not known?

A What happened of

B What happened in

C What is that happens to

D What happened to

E No correction required

ANS:D - What happened to

No answer description is available.