Which of the phrases (A), (B), and (C) give below should replace the phrase given in bold in the following sentence to make the sentence grammatically mmeaningful and correct. If the sentence is correct as it is and ' No correction is required', mark (D) as the answer. On of the factor for her failure is the lack of concern for others.

• A. On off the factors
• B. The mainly factor
• C. No correction required
• D. One of the factor