The average year-after-year conditions of temperature and precipitation in a particular region is the region's

a. weather.

c. ecosystem.

b. latitude.

d. climate.

Latitude does not change depending on the precipitation, but it remains stable, so it can't be the correct answer.

Precipitation and temperature are two aspects which make up the weather, but a weather is rather a short-term phenomenon. Its long-term equivalent is climate and this is also the correct answer.