Which polynomial contains the powers in descending order?
a.4x5 - 2x2 - x3 + 3x4 + 1
b.4x5 + 3x4 - x3 - 2x2 + 1
c.1 - 2x2 - x3 + 4x5 + 3x4
d.3x4 - x3 +4x5 - 2x2 + 1