Which sentence has correct subject-verb agreement?
- The price of the tickets are surprising.
- The keys to the cabinet has gone missing.
- The recipe for these cookies need more sugar.
- The stack of old newspapers was recycled.
Why D? And why not the others?
Correct answer: D. The stack of old newspapers was recycled.
A verb must agree with its true subject, which is the main (head) noun of the subject phrase — not whatever noun happens to sit closest to the verb inside a describing phrase. In 'the stack of old newspapers', the head noun is the singular 'stack' ('of old newspapers' just describes which stack), so the singular verb 'was' is correct. The ticket-price sentence makes the opposite mistake: its head noun is the singular 'price' ('of the tickets' only describes the price), so it needs 'is', not the plural 'are' that got pulled in by the nearby plural 'tickets'. The keys sentence has the reverse problem: its head noun is the plural 'keys' ('to the cabinet' just describes which keys), so it needs the plural 'have', not the singular 'has' pulled in by the nearby singular 'cabinet'. The recipe sentence fails the same way as the price sentence: the head noun is singular 'recipe', so it needs 'needs', not 'need'.
Source: BBC Bitesize KS3 English: Grammar — subject-verb agreement