Under the Road Traffic Act and its subordinate regulations, which pair lists signs that are caution signs, like the traffic safety signs in the picture?

Answer: ① Uphill slope sign, frequent congestion section sign

The pictured crosswind and wildlife signs are caution signs (yellow triangles). The uphill slope and frequent congestion signs are also caution signs. Width limit and following-distance signs are regulatory signs, while tram-only road, detour, unprotected left turn, and left turn and U-turn signs are instruction signs. [Enforcement Rules of the Road Traffic Act, Annex 6, Caution signs No. 137, 139]