Sentence improvement: convert the indirect question to the correct past form Original sentence: "What happens to all those travellers on the ship was not known?" Select the option that forms a correct content clause.

Given data

• Matrix clause: "… was not known."
• Embedded wh- clause should be a statement, not a direct question.

Concept/Approach
In indirect questions/content clauses, we use normal statement word order and match the time frame: with "was not known", we need past reference: "What happened to … was not known." Also, no question mark is needed for the overall declarative sentence.

Option analysis
What happened to — correct preposition "to" with "happen" and correct tense/order. ✅What happened of — wrong preposition; not idiomatic.What happened in — wrong preposition.What is that happens to — present tense; unnecessary "that".

Final Answer
What happened to all those travellers … was not known.