Choose the segment with an error; if none, select ‘‘No error.’’ Sentence: The observers felt that the stronger team had to face defeat because the players didn't play whole hearted.

Introduction / Context:
This item checks correct part of speech and adverb formation. After verbs like ‘‘play,’’ an adverb should modify the manner of action, not an adjective.

Given Data / Assumptions:

• Target expression: ‘‘play wholeheartedly’’ (adverb).
• Given form: ‘‘whole hearted’’ (adjective, even spaced incorrectly).

Concept / Approach:
Use the adverb form to modify verbs: adjective → adverb by adding ‘‘-ly’’ (‘‘wholehearted’’ → ‘‘wholeheartedly’’). Also, the compound is typically written solid: ‘‘wholehearted(ly).’’

Step-by-Step Solution:
Identify modifier role: it modifies ‘‘play’’ → needs adverb.Form adverb: ‘‘wholeheartedly.’’Correct sentence: ‘‘… because the players didn’t play wholeheartedly.’’

Verification / Alternative check:
Try substituting a clear adverb like ‘‘well’’—‘‘didn’t play well’’ confirms that an adverbial form is required.

Why Other Options Are Wrong:
A–C are acceptable; the cause–effect structure is fine. The only clear grammatical error is in D.

Common Pitfalls:
Using adjectives where adverbs are required; splitting compounds (‘‘whole hearted’’) that are normally closed (‘‘wholehearted’’).

Final Answer:
didn't play whole hearted.