Step 1: Understanding the Concept:
Livestock housing requires proper ventilation.
Different components serve different functions.
Step 2: Key Formula or Approach:
No specific formula.
Need to know ventilation components.
Step 3: Detailed Explanation:
A continuous ridge opening is an outlet ventilator.
It allows hot air to escape from the top of the shed.
It is not for lighting or forced ventilation.
It is an outlet for warm air.
Thus, it is an outlet ventilator.
Step 4: Final Answer:
Continuous ridge opening is an outlet ventilator.
Hence, the correct option is (D).