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. At Currently estimates, the cost of modernizing the airport Would be more than double the carlier estimate

• A. On current estimates
• B. By Currently estimates
• C. No correction required
• D. At current estimates