Answer:
Step-by-step explanation:
If we put this polynomial (yes it is a polynomial) in order of descending powers of x, it would be

The definition of a polynomial is an expression of more than 2 algebraic terms, especially the sum of several terms that contain different powers of the same variable(s).
Not just a sum. A difference too, but since every subtraction problem can be written as an addition, that's why they say "the sum of several terms". The degree of the polynomial is the same as the highest power of x. Ours is a 4th degree. The leading coefficient is the first number that leads the polynomial when it is put into order of descending powers of x. Our coefficient is -3. To sum up:
Yes, it is a polynomial; it is a degree 4 with a leading coefficient of -3
That is choice C