His constant tardiness was (A)/ no longer an excuse to (B)/his lack of responsibility in (C)/ meeting project deadlines (D).

Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. The corresponding letter of that part is the answer. If the given sentence is correct as it is, then choose option ‘No error’ as the answer response. (Ignore errors of punctuation, if any).

The correct option/answer is B.

Let's analyze the sentence part by part to identify the grammatical/prepositional error:

Part (A): "His constant tardiness was"
This part is grammatically correct. The subject "His constant tardiness" is singular and correctly takes the singular past tense verb "was".

Part (B): "no longer an excuse to"
This part contains an error in preposition usage. The noun "excuse" takes the preposition "for" (or sometimes "of" depending on context, but standard phrasing here is "an excuse for [something]") when indicating a reason or justification for a behavior or condition.
Using "to" after the noun "excuse" in this context is incorrect. It should be modified to "no longer an excuse for".

Part (C): "his lack of responsibility in"
This part is correct. "his lack of responsibility" properly follows the preposition "for", and "in" correctly connects to the action/area of responsibility.

Part (D): "meeting project deadlines"
This part correctly completes the prepositional phrase ("in meeting project deadlines").

Corrected Sentence:
"His constant tardiness was no longer an excuse for his lack of responsibility in meeting project deadlines."

Therefore, the error lies in part (B).