Read each sentence to find out whether there is any error in any part. Select the part that contains an error, or choose No error if the sentence is grammatically correct: Coleridge as well as Wordsworth were of the opinion that the opposite of poetry is not prose but science.

Introduction / Context:
This error detection question examines your understanding of subject verb agreement when two nouns are joined by as well as. The sentence talks about the poets Coleridge and Wordsworth and their shared opinion about poetry and science. While the meaning may seem clear, there is a subtle grammatical issue related to the verb that must be identified and corrected.

Given Data / Assumptions:
- The sentence is divided into parts: (a) Coleridge as well as Wordsworth were, (b) of the opinion that the opposite of poetry is, (c) not prose but science, and (d) No error.
- The subject phrase uses as well as between two names.
- We need to find whether the verb were is correct for this subject construction.

Concept / Approach:
When two nouns are linked by as well as, along with, together with, and similar expressions, the verb usually agrees with the first noun, which is treated as the main subject. In this sentence, the first noun is Coleridge, which is singular. The phrase as well as Wordsworth adds extra information but does not turn the subject into a true compound plural. Therefore, the verb must also be singular and should be was instead of were. This means that part a is where the error lies.

Step-by-Step Solution:
Step 1: Focus on the subject phrase Coleridge as well as Wordsworth and identify Coleridge as the main subject.
Step 2: Recall the rule that as well as does not change the number of the grammatical subject; the verb must agree with the first noun.
Step 3: Note that Coleridge is singular and conclude that the verb should be singular was, not plural were.
Step 4: Recognise that the rest of the sentence of the opinion that the opposite of poetry is not prose but science is grammatically correct, so the only error is in part a.

Verification / Alternative check:
Rewrite the sentence with the correct verb: Coleridge as well as Wordsworth was of the opinion that the opposite of poetry is not prose but science. This version follows the subject verb agreement rule and still clearly communicates that both poets shared the same opinion. The structure is consistent with exam level grammar rules, which treat as well as as an additive phrase rather than a pure coordination creating a plural subject.

Why Other Options Are Wrong:
- Part b: of the opinion that the opposite of poetry is is correct; the verb is properly matches the singular noun opposite.
- Part c: not prose but science correctly completes the comparison and contains no grammatical error.
- Part d and option e suggesting no error are both incorrect because we have identified a clear subject verb agreement problem in part a.

Common Pitfalls:
Many exam takers see two names separated by as well as and instinctively choose a plural verb, assuming there is a compound subject. However, exam grammar rules treat this structure differently from simple coordination with and. A good practice is to temporarily remove the as well as phrase and read the sentence with only the first noun. If Coleridge was of the opinion sounds correct and Coleridge were of the opinion sounds wrong, you have a clear hint that the singular verb is required.

Final Answer:
The error is in Part a; the verb should be singular was, not plural were.