Final answer:
Longitude is not a direct factor in determining a region's climate, while elevation, proximity to water, and ocean currents are.
Step-by-step explanation:
Several factors interact to produce a region's specific climate. Factors such as elevation, latitude, wind systems, ocean currents, position on a continent, and mountain barriers are all crucial in determining temperature, precipitation, and the overall distribution of climate regions. However, longitude is not typically considered a direct factor in determining a region's climate. Therefore, the correct answer to the question is A) Longitude.