This is a proof question I have no idea what to begin with...someone please make it possible

Question 1: Are the following sets of polynomials subspaces of all polynomials of degree less than or equal to 4?

a) Even polynomials of degree less than or equal to 4

b) Odd polynomials of degreeless than or equal to 4

c) Polynomials of degree 4

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Question 2: Give two polynomials that span the space of all polynomials in one variable x of degree less than or equal to 1