Determine whether the given set is a subspace of the vector space .
A.
, and is the subset of consisting of those functions satisfying the differential equation
B.
, and is the set of vectors of the form
C.
, and is the subset of consisting of those polynomials satisfying
D.
is the vector space of all real-valued functions defined on the interval , and is the subset of consisting of those functions satisfying
E.
, and is the subset of consisting of those polynomials satisfying
F.
, and is the set of solutions to the homogeneous linear system where is a fixed matrix.
G.
, and is the subset of all upper triangular matrices.