Which of these are correct?

Question

If E = elasticity modulus, I = moment of inertia about the neutral axis and M=bending moment in pure bending under the symmetric loading of a beam, the radius of curvature of the beam:

1. Increases with E

2. Increases with M

3. Decreases with I

4. Decreases with M

Which of these are correct?

(a) 1 and 3                      (b) 2 and 3

(c) 3 and 4                      (d) 1 and 4