To determine the slant height of a cone, you typically can use the Pythagorean theorem. The slant height (l) of a cone can be calculated using the formula:
\[ l = \sqrt{r^2 + h^2} \]
where \( r \) is the radius of the base, and \( h \) is the height of the cone.
Unfortunately, without the specific values for the radius and height of the cone, I can't directly calculate the slant height or determine which of the provided responses is correct. However, if the problem implies using the Pythagorean Theorem, the responses suggesting "Use the Pythagorean Theorem" (specifically 9.8 ft and 12 ft) are likely your best options.
If you have the radius and height values, I can help you compute the slant height!