Co-efficient of wind resistance of a circular surface, is

• A. <img src="/_files/images/civil-engineering/theory-of-structures/89-21-94-3.png">
• B. <img src="/_files/images/civil-engineering/theory-of-structures/89-21-94-4.png">
• C. <img src="/_files/images/civil-engineering/theory-of-structures/88-21-88-1.png">
• D. <img src="/_files/images/civil-engineering/theory-of-structures/88-21-88-2.png">