In displacement-based plate theories, which assumption of Classical Plate Theory is relaxed in Shear Deformation Theory?

• A. A straight-line perpendicular to the plane of the plate is inextensible
• B. A straight line perpendicular to the plane of the plate remains straight
• C. A straight line perpendicular to the plane of the plate rotates such that it remains perpendicular to the tangent to the deformed surface
• D. A straight line perpendicular to the plane of the plate rotates