Explanation:

- The sentence is broken down into four parts: (A) "Outright rejection," (B) "of my plea," (C) "disappointed me a lot," and (D) "No error."

- Option 1 (A) suggests there's an error in "Outright rejection," but it is grammatically correct.

- Option 2 (B) indicates a problem with "of my plea," though it correctly follows the structure after "rejection."

- Option 3 (C) evaluates "disappointed me a lot." This phrase is appropriate and well-constructed.

- Option 4 (D) claims there is no error, implying the sentence is correct as is.

Given this analysis, the sentence appears free from grammatical errors.

Correct Answer: Option 4 (D)