In which climate can exterior finish generally be installed directly over the stud?

The correct choice is mild climates because in these conditions, the temperature range and humidity levels are generally stable, allowing for exterior finishes to be installed directly over the studs. In mild climates, there's less risk of moisture accumulation, which can lead to issues such as mold or deterioration of the materials. Additionally, slight expansion or contraction of the materials can be managed effectively without the need for additional barriers, making installation simpler and more efficient.

Arid climates, while dry, can experience large temperature fluctuations that affect the expansion and contraction of materials. Cold climates often require additional insulation and vapor barriers to prevent moisture issues due to snow and ice, while tropical climates usually have high humidity, which complicates straightforward installation methods and requires extensive moisture protection to prevent damage.