You're told there is a 10th degree polynomial. There are four roots of multiplicity 1 and one of multiplicity 2 (a double root).
Anytime there is a root of multiplicity 1 of a polynomial, its graph crosses the x-axis at that root. Anytime there is one of multiplicity 2, it means that we count the root twice and the graph has a tangency point.
The degree of a polynomial tells you how how many roots it has. Ours is degree 10, so it has ten roots. We have the four roots of multiplicity 1 and the one of multiplicity two, for a total of 6. (four and two).
So there are six real roots.
The rest of the roots are imaginary and non-real, and 10 - 6 = 4. So there are four imaginary roots.
Thus choice C is best.
