A simply supported beam of overall depth 150 mm has neutral axis at 50 mm from extreme top fibre. Permissible flexural stresses in extreme compression and extreme tension fibre are restricted to 15 MPa and 25 MPa respectively. If the load on the beam is increased gradually, then:

• A. failure of section will be due to stresses in extreme top fibre reaching to maximum permissible tensile stresses
• B. failure of section will be due to stresses in extreme in extreme bottom fibre reaching to maximum permissible tensile stresses
• C. failure of section will be due to stresses in extreme bottom fibre and extreme top fibre reaching to maximum permissible tensile and maximum permissible compressive stresses simultaneously
• D. failure of section will be due to stresses in extreme top fibre reaching to maximum permissible compressive stresses