Correct answer is (a) It is element-wise constant for triangular element whereas not a constant for quadrilateral element

The best explanation: In the study of plane elasticity problems, the first derivatives of the shape function S for a triangular element are element-wise constant, whereas, for a quadrilateral element, they are not constant. Notably, \(\frac{\partial s (n, e)}{\partial n}\) is linear in e and constant in n whereas \(\frac{\partial s (n, e)}{\partial e}\) is linear in n and constant in e.