Task: Class Definition Understanding (ontology: Earth_Environment/EnvironmentOntology)

Which of the following definitions best describes 'anafront'?

A. A weather front at which warm air is ascending to high altitudes along the frontal surface.
B. A weather front which is part of a mass of upper air.
C. A weather front which separates air masses of tropical and polar origin.
D. A weather front at which warm air is descending to lower altitudes along the frontal surface.

Answer: A weather front at which warm air is ascending to high altitudes along the frontal surface.