What type of mechanical braking system (sistema de frenos) should be installed on an animal-drawn cart for safe operation in hilly terrain?

1. No brakes are needed; the horse must stop the entire loaded cart with its collar alone
2. A manual lever or screw-operated friction brake (freno de palanca, zapata o disco) acting directly on the cart wheels to assist the draft animal during deceleration and prevent the cart from pushing the animal downhill
3. An electric regenerative motor brake
4. An air parachute