Sentence improvement (word order and aspect): determine whether a correction is required Original sentence: "They were all shocked at his failure in the competition." Choose the best option; if the sentence is already correct, select "No correction required".

Assessment
The original sentence is idiomatic: “were all shocked at …” correctly places “all” after the auxiliary and uses the preposition “at” with “shocked”.

Why other options fail

• “were shocked at all” — changes meaning (“at all” = to any extent) and misplaces “all”.
• Perfect forms (“had … shocked”) misrepresent the state as an action and mishandle participles/prepositions.
• “on” is the wrong preposition after “shocked”.

Final Answer
No correction required.