Within M₃ₓ₃ (the set of all 3x3 matrices), let Wₕ be the subset of matrices of the form [[a,4,b],[a,b,c],[b,c,c]]. It turns out that the set Wₕ is a subspace of M₃. For any matrix of the f
(a) Line
(b) Plane
(c) Sphere
(d) Hyperplane