80. As shown in the figure, the slant height of the cone $O A=6$, and the radius of the base circle is 2. A small insect starts at point $A$ on the base of the cone, travels around the lateral surface of the cone, and returns to point $A$. The shortest distance the insect travels is $\qquad$
A. 12
B. $4 \pi$
C. $6 \sqrt{2}$
D. $6 \sqrt{3}$
Answer: D