Error spotting — necessity vs. modal usage: Select the erroneous part (A/B/C) — mark D if correct — 'It is necessary / that everybody / must have a house. / No error.'. Evaluate redundancy and standard subjunctive/modal patterns in formal English.

Given data

• Parts: (A) It is necessary (B) that everybody (C) must have a house. (D) No error.

Concept/Approach: Subjunctive/mandative 'that' vs. modal 'must'
In formal English, after mandative 'It is necessary/essential that…', we either use the bare subjunctive ('everybody have') or a modal like 'should'. Combining 'necessary' with 'must' is stylistically redundant and often marked wrong in exams.

Step-by-step correction
1) Identify structure: 'It is necessary that…'2) Choose one correct completion:• Subjunctive: 'that everybody have a house.'• With 'should': 'that everybody should have a house.'3) Avoid 'must' here to prevent redundancy.

Verification/Alternative
'It is necessary for everybody to have a house' also works ('for + NP + to-infinitive').

Common pitfalls
Stacking strong necessity marker 'must' on top of 'It is necessary that…'

Final Answer
Part C 'must have a house.' is the flagged error; use subjunctive 'have' or 'should have'.