English grammar error-spotting (correlative ‘‘as … as …’’—do not pair ‘‘as’’ with ‘‘or’’): Find the erroneous part among A–D; pick ‘‘No error’’ only if none is wrong. ‘‘An animal / can be just as unhappy in a vast area / or in a small one / No error.’’

Given data

• B uses the correlative opener ‘‘as’’
• C incorrectly uses ‘‘or’’

Concept / Approach
The correlative construction must be ‘‘as … as …’’ not ‘‘as … or …’’. The second limb should read ‘‘as in a small one’’ to preserve symmetry.

Correction
‘‘An animal can be just as unhappy in a vast area as in a small one.’’

Verification
Both prepositional phrases now balance and the comparison is well-formed.

Final Answer
or in a small one