Step 1: Understanding the Question:
This question tests knowledge of shelterbelts and windbreaks.
Step 2: Detailed Explanation:
Shelterbelts and windbreaks are most useful in arid and semi-arid areas.
They protect against wind erosion and desiccation.
Humid (A): Less need for windbreaks.
Temperate (C): Moderate need.
Alpine (D): Not common.
Thus, the correct answer is arid and semi-arid.
Step 3: Final Answer:
Thus, shelterbelts are most useful in arid and semi-arid areas, which corresponds to option (B).
[0.5cm]