Figure below shows a mass of 300 kg being pushed using a cylindrical rod made of a material having E = 22 MPa and of 2 m length and 0.1 m in diameter. In order to avoid the failure of the rod due to elastic instability, the maximum value of the co-efficient of Coulomb friction permissible between the mass and the floor is

• A. 0.22
• B. 0.36
• C. 0.65
• D. 0.75