Which of these statements are correct?

Question

Consider the following statements:

If at a section distant one of the ends of the beam, M represents the bending moment V the shear force and w the intensity of loading, then                            

1. $\frac{dM}{dx} = V$

2.$\frac{dV}{dx} = w$

3.$\frac{dw}{dx} = y$

(the deflection of the beam at the section)

Which of these statements are correct?

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

(c) 2 and 3                   (d) 1,2 and 3