In a beam the local bond stress Sb, is equal to

• A. <img src="/_files/images/civil-engineering/rcc-structures-design/71-13-25-1.png">
• B. <img src="/_files/images/civil-engineering/rcc-structures-design/71-13-25-2.png">
• C. <img src="/_files/images/civil-engineering/rcc-structures-design/71-13-25-3.png">
• D. <img src="/_files/images/civil-engineering/rcc-structures-design/71-13-25-4.png">
• E. None of these.