ANSWER :
C. 5
EXPLANATION :
The Leading coefficient is the coefficient of the leading term.
The leading term is the term with the highest degree.
From the problem, we have the polynomial :
![f(x)=9-2x+6x^2+5x^3](https://img.qammunity.org/2023/formulas/mathematics/college/fhyzxw3kslsrk22aqjj8mbdzmgnvbclm6e.png)
The term with the highest degree is 5x^3
Therefore, the leading coefficient is 5