A thick cylindrical shell having ro and ri as outer and inner radii, is subjected to an internal pressure (p). The minimum tangential stress at the outer surface of the shell is

• A. <img src="/_files/images/mechanical-engineering/strength-of-materials/120-392-1.png">
• B. <img src="/_files/images/mechanical-engineering/strength-of-materials/120-392-2.png">
• C. <img src="/_files/images/mechanical-engineering/strength-of-materials/120-392-3.png">
• D. <img src="/_files/images/mechanical-engineering/strength-of-materials/120-392-4.png">