Identify the part which contains an error.
He is / suffering from / pneumonia / for a week now.

Correct option is A

Error part: (a) He is
Correct form: He has been / He has been suffering from pneumonia for a week now.
Detailed explanation:
• The phrase “for a week now” shows a duration that started in the past and continues up to the present.
• For such duration + continuing action/state, we generally use Present Perfect Continuous: has/have been + V-ing.
• “He is suffering…” is present continuous, but it does not naturally fit with long duration like “for a week now” in exam-standard grammar.
Grammatical rule (English):
• Duration (for/since) + continuing action → Present Perfect Continuous (has/have been + V-ing)
व्याकरणिक नियम (Hindi):
• for/since से समयावधि आए और क्रिया अभी तक जारी हो, तो Present Perfect Continuous आता है: has/have been + verb-ing।
Why other parts are correct (meanings included):
• (b) suffering from → सही collocation (Hindi: से पीड़ित होना)
• (c) pneumonia → बीमारी का नाम (Hindi: निमोनिया)
• (d) for a week now → सही duration phrase (Hindi: एक सप्ताह से अब तक)
Hence, option (a) is the correct answer.