English grammar error-spotting (intransitive ‘‘enjoy’’ needs a reflexive object and adverb placement): Read the sentence parts (A–D) and find the incorrect segment; select ‘‘No error’’ only if the whole sentence is correct: ‘‘They / enjoyed thoroughly / at the party. / No error.’’

Given data

• A: ‘‘They’’
• B: ‘‘enjoyed thoroughly’’
• C: ‘‘at the party.’’
• D: ‘‘No error.’’

Concept / Approach
In idiomatic English, ‘‘enjoy’’ is normally transitive and, for self-enjoyment, takes a reflexive object (‘‘enjoyed themselves’’). Also, the adverb ‘‘thoroughly’’ is best placed after the object.

Step-by-step evaluation
Correct pattern: ‘‘They thoroughly enjoyed themselves at the party.’’Therefore, the error is in Part B: ‘‘enjoyed thoroughly’’.

Correction
‘‘They thoroughly enjoyed themselves at the party.’’

Common pitfalls

• Using ‘‘enjoy’’ without an object in this meaning.
• Awkward adverb placement obscuring natural rhythm.

Final Answer
enjoyed thoroughly