The inverse of a conditional statement "If P, then Q" is "If not P, then not Q."
For the conditional statement "If the figure is a triangle (P), then the figure has three sides (Q)," the inverse would be:
"If the figure is not a triangle (not P), then the figure does not have three sides (not Q)."
So, the correct answer from your options is:
If the figure is not a triangle, then the figure does not have three sides.