Choose the grammatically correct version of the sentence given below:

He was neither interested in the project or willing to contribute to the team’s efforts.

Option A is the correct answer.

"Neither...nor" is the correct correlative conjunction pair to use for showing a negative choice between two alternatives. Using "neither...or" as in the original sentence is grammatically incorrect.

Option B: "Neither...and nor" is redundant and incorrect. The structure requires only "nor" after "neither."
Option C: The inclusion of "he was" after "nor" is unnecessary and disrupts the flow of the sentence.
Option D: "Nor was willing" is grammatically awkward; it should follow the same structure as the first clause for parallelism.
Option E: The original sentence is incorrect because "neither...or" is grammatically incorrect.