Read the sentence carefully to determine whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. Select the letter corresponding to that part as your answer. If the sentence is grammatically correct as it is, choose 'No error' as your answer response. (Ignore errors of punctuation, if any).

The principal requested that every teacher (A)/ submits their annual lesson plans (B)/ before the end of the week (C)/ without any further delay (D).

The correct option is B.

Explanation:
Part (B) contains a grammatical error involving the mandative subjunctive mood.

When verbs that express a request, command, demand, or suggestion (such as requested, demanded, recommended, or insisted) are followed by a that-clause, the verb inside the clause must be in its subjunctive mood (the bare infinitive/base form of the verb), regardless of whether the subject is singular or plural.

In the sentence:
"The principal requested that every teacher (A) / submits their annual lesson plans (B)..."

The verb submits (indicative form) should be changed to its base form submit (subjunctive form) after the verb requested that.

Correct Sentence:
"The principal requested that every teacher submit their annual lesson plans before the end of the week without any further delay."

Hence, the error is in part (B).