Which is a quadratic function?

A) f (x) = 2x + x + 3

B) f (x) = 0x2 - 4x + 7

C) f (x) = 5x2 - 4x + 5

D) f (x) = 3x3 + 2x + 2

Option c is a correct option because the eq. given in it have higgest degree of two but eq. 2 in option b is not a quadratic equation because the coeffienct of x^2 is 0 and it will average out this value to 0

And in option 1 the higgest degree is 1 and in option 4 the highest degree is 3