If a beam supports two concentrated loads, then the shape of profile followed by cable is:

Explanation:

(i) Cable is a structural element that can resist only tension. It cannot resist shear, bending, and compressive forces.

(ii) The shape of a cable suspended between two supports is defined by the help of applied load. And the shape of cable is the equivalent to the shape of bending moment diagram of simply supported beam subjected to the same loading as the cable.

Given, Beam supports two concentrated loads

Following are the figure for SFD & BMD

As Bending Moment Diagram is Trapezoidal 

Option 3 is correct.

Additional Information

(iii) If a concentrated load is acting on a cable, shape will be triangle because bending moment diagram of simply supported beam subjected to concentrated load is triangular. 

(iv) Similarly, if cable subjected to Horizontal UDL, then BMD of simply supported beam has parabolic shape and hence, shape of cable is also parabolic.

(v) If UDL on cable is not horizontal or due to its self weight, cable will take the Catenary shape.

(vi) The girder in a suspension bridge transmits to its supports require a little load.