The correct option is (a) Linear in e and constant in n

Explanation: For a quadrilateral element, the first derivatives of the shape function are not constant. \(\frac{\partial s}{\partial n}\) is linear in e and constant in n whereas \(\frac{\partial s}{\partial e}\) is linear in n and constant in e. Also, the first derivatives of shape functions for a triangular element are constant element wise, and hence all the strains computed are constant element wise.