The following sentence has been divided into parts. One of them may contain an error. Select the part that contains the error.

He was neither interested in the opera (A)/ nor he wanted (B)/ to spend money (C)/ on the concert tickets. (D)/ No error

To identify the error in the sentence, let's analyze its grammatical structure step-by-step.

The sentence uses the correlative conjunction pair "neither... nor". Correlative conjunctions must connect grammatically parallel structures.
Let's look at the two parts being connected:
1. After "neither", we have "interested in the opera" (an adjective phrase/predicate complement).
2. After "nor", we have "he wanted to spend money..." (a clause with a subject "he" and verb "wanted").

Because the structure following "neither" is a predicate adjective/prepositional phrase, the structure following "nor" should also be parallel. To make the sentence parallel and grammatically correct, we can rewrite it using inversion or by matching the structures:
- Parallel adjective/prepositional phrases: "He was neither interested in the opera nor willing to spend money..."
- Parallel clauses (with inversion after 'nor'): "He was neither interested in the opera, nor did he want to spend money on the concert tickets."

The phrase "nor he wanted" in part (B) violates parallelism because it introduces an un-inverted subject-verb clause ("he wanted") after "neither" was followed by a simple adjective phrase. To fix this, it should be changed to "nor did he want" to maintain correct grammatical inversion after the negative coordinator "nor".

Therefore, the part containing the error is B.