Final answer:
Option (C), In canoe slalom, red and green gates signify 'Left and Right' passage for competitors, with red for upstream and green for downstream.
Step-by-step explanation:
The two colors red and green on the numbered gates in the canoe slalom represent 'Left and Right'. In the canoe slalom sport, the red gates require athletes to navigate through them in an upstream direction, which is often more challenging due to the current. In contrast, green gates indicate that athletes should move through them in a downstream direction, which is typically faster and with the current.