A concentrated force $P$ is applied to a beam, which creates a moment on cross$-$section B$.$

Use arrows to identify the points $(3$D stress elements$)$ on section B with the greatest shear stress, tensile stress and compressive stress. Clearly label the points on the bolded vertical surface: "max shear", "max tension", "max compression"$).[3$ pts$]$

$3.$ Sketch the shear and moment diagram for beam A$-$B$.$ You do NOT need to enter shear and moment magnitudes in the diagrams, just sketch the diagrams. $[3$ pts$]$

Extra Credit: Clearly explain the benefits of using the $4-$point bending test configuration in the above problem to measure the mechanical response of structures subjected to bending loads. $[1$ pts$]$