The diameter of the cone is given as 8. The radius is half of the diameter.
To find the radius, you can use the formula:
\[ \text{Radius} = \frac{\text{Diameter}}{2} \]
Substituting in the given diameter:
\[ \text{Radius} = \frac{8}{2} = 4 \]
Thus, the radius of the cone is 4.
So the correct response is:
4