Which of the following algebraic expression is a polynomial?
A. 5^(2-x)
B. 〖4x〗^(-2)+1
C. 2+x
D. 7/x^2

Which of the following algebraic expression is not a polynomial?
A. 8^2
B. 〖3x〗^(-2)
C. 2+x
D. 7/3^2​