In the sentence "Police reports claim that substantial seizure of cocaine have been made in the last two months," one part contains an error in subject–verb agreement. Identify the incorrect part.

Introduction / Context:
This error spotting question focuses on subject–verb agreement in a complex noun phrase. The sentence "Police reports claim that substantial seizure of cocaine have been made in the last two months" sounds slightly off to a trained ear. The task is to find the segment where the verb form does not correctly match its subject in number, a very common area of testing in grammar-based examinations.

Given Data / Assumptions:

• Complete sentence: Police reports claim that substantial seizure of cocaine have been made in the last two months.
• Key segments:
  • Part 1: Police reports claim that
  • Part 2: substantial seizure of cocaine have been made
  • Part 3: in the last two months.
  • Part 4: No error
• We must identify which part contains incorrect grammar, particularly focusing on agreement.

Concept / Approach:
The central rule is that the verb must agree with the true subject in number. In the phrase "substantial seizure of cocaine have been made," the head noun is "seizure," which is singular. The prepositional phrase "of cocaine" merely describes what is seized and does not change the number of the head noun. Therefore, the verb should be singular ("has been made"), not plural ("have been made"). The rest of the sentence is structurally sound.

Step-by-Step Solution:

Step 1: Identify the clause where the error may occur: "substantial seizure of cocaine have been made." Step 2: Find the true subject of the verb "have been made." The noun closest to the verb is "seizure," which is singular. Step 3: Note that the phrase "of cocaine" is a prepositional phrase modifying "seizure" and does not act as the subject. Step 4: Apply subject–verb agreement rules: a singular subject requires a singular verb, so "have been made" must change to "has been made." Therefore, Part 2 contains the error.

Verification / Alternative check:
If we correct the sentence, it becomes: "Police reports claim that substantial seizure of cocaine has been made in the last two months." This version sounds grammatically correct and respects the singular–plural relationship between "seizure" and "has been made." The rest of the structure stays unchanged, confirming that the only issue lay in the plural verb form.

Why Other Options Are Wrong:

Option A: "Police reports claim that" is correct. "Police reports" is plural, so "claim" is the correct plural verb. Option C: "in the last two months." is a correct adverbial phrase of time and contains no subject–verb agreement issues. Option D: "No error" is incorrect because we have clearly identified an agreement error in Part 2. Option E: "The sentence is fully correct as written." is also wrong for the same reason; the verb form must be singular.

Common Pitfalls:
A very common mistake is to let the noun immediately after the preposition "of" influence the verb form. In phrases like "a list of items," "a bouquet of flowers," or "substantial seizure of cocaine," the true subject is the noun before "of" (list, bouquet, seizure). Many learners incorrectly match verbs to the plural noun that follows "of," resulting in errors like "a bouquet of flowers were" instead of "was." Always locate the head noun of the phrase and ensure the verb agrees with that noun, not with any noun inside a prepositional phrase.

Final Answer:
The incorrect part of the sentence is substantial seizure of cocaine have been made.