The correct choice is (a) The first derivatives of S and hence, all the strains are element-wise constant

To explain: A linear triangular element (number of nodes=3) has two degrees of freedom, ux and uy per node and a total of six nodal displacements per element. Since the shape functions are linear, their first derivatives are element-wise constant, and hence, all the strains computed for the linear triangular element are element-wise constant.