Final answer:
An average year round temperature of above 90 degrees classifies an area as a tropical climate.
Step-by-step explanation:
The characteristic that classifies an area as a tropical climate is an average year round temperature of above 90 degrees (option A). The tropical type A climate is usually found in the tropics and has warm temperatures throughout the year with a high level of precipitation. These climates have various subgroups that indicate how rainfall is distributed, some having a dry season and wet season, while others receive consistent rainfall throughout the year.