If b is the width of a plate joined by diamond riveting of diameter d, the efficiency of the joint is given by

• A. <img src="/_files/images/civil-engineering/strength-of-materials/124-6.29-1.png">
• B. <img src="/_files/images/civil-engineering/strength-of-materials/124-6.29-2.png">
• C. <img src="/_files/images/civil-engineering/strength-of-materials/124-6.29-3.png">
• D. <img src="/_files/images/civil-engineering/strength-of-materials/124-6.29-4.png">