In the Shear Deformation plate theory, what characteristic contributes to shear locking?

(a) Transverse shear strains in thick plates present computational difficulties

(b) Transverse shear strains in thin plates present computational efficiency

(c) For thick plates, the element stiffness matrix yields erroneous results for the generalized displacements

(d) For thin plates, the element stiffness matrix becomes stiff and yields erroneous results

This question was addressed to me in an interview for internship.

The question is from Shear Deformable Plate Model in section Bending of Elastic Plates of Finite Element Method