If Re is the Renold's number, the coefficient of friction for laminar flow is

• A. <img src="/_files/images/civil-engineering/hydraulics/160-7.253-1.png">
• B. <img src="/_files/images/civil-engineering/hydraulics/160-7.253-2.png">
• C. <img src="/_files/images/civil-engineering/hydraulics/160-7.253-3.png">
• D. <img src="/_files/images/civil-engineering/hydraulics/160-7.253-4.png">