Read the following sentence to determine if there is any grammatical error in any of its parts.

She was neither eager to attend the seminar (A)/ nor she desired (B)/ to participate in (C)/ the interactive workshop. (D)/ No error

The correct option is B.

Explanation:
In part (B) of the sentence, "nor she desired" contains a grammatical error.
When using the correlative conjunction neither... nor..., parallel structure must be maintained between the elements being joined. In part (A), "neither" is followed by an adjective phrase ("eager to attend the seminar"). Therefore, "nor" in part (B) should also be followed by a parallel grammatical structure.
Additionally, when "nor" links clauses, inverted word order (auxiliary verb before subject, e.g., "nor did she desire") is required.

Corrected Sentence:
"She was neither eager to attend the seminar nor desirous to participate in the interactive workshop."
or
"She neither wished to attend the seminar nor desired to participate in the interactive workshop."