If a(x) is a polynomial function and b(x) is a polynomial function, then which of the following could be the sum of a(x) + b(x)? A. ex + 2B. x2 + 2x − log(x)C. x6 − x4 + 9xD. 5x² − 3x

The sum of two polynomial functions will also be a polynomial function. The exponents of the variables in the polynomial function are non-negative integers. Option A is an exponential function. Option B is a logarithmic function. 

The formatting is not proper in the options C and D. Only 1 option can be the correct answer.

If the options are:

[tex]C) x^{6} - x^{4} +9x \\ \\ D) 5x^{2} -3^{x} [/tex]

Then option C would be the correct answer as in option D variable is in the exponent which is against the definition of polynomial function.

If the options are:

[tex]C) x^{6} - x^{4} +9^{x} \\ \\ D) 5x^{2} -3x[/tex]

Then option D would be the correct answer as in option C variable is in the exponent which is against the definition of polynomial function.