Draw three paths, not intersecting and each within the gold region, that join A to A, B to B, and C to C.
Here's the easy way to answer this puzzle:
No thinking is involved. No backtracking is involved. You just draw in an answer.
The presentation of the puzzle uses a little misdirection, which I assume is deliberate. The order "A,B,C" encourages the solver to try A first. If the letters A and C were swapped, I think most people would find the puzzle easy.
This answers puzzle 3 at A technique in solving puzzles.