As per the maximum principal stress theory, when a shaft is subjected to a bending moment M and torque T, and if is the allowable stress in axial tension, then the diameter 'd' of the shaft is given by

• A. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/17-700-1.png">
• B. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/17-700-2.png">
• C. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/17-700-3.png">
• D. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/17-700-4.png">