What is a boundary between two air masses called?

• A. A boundary between two air masses
• B. A type of storm associated with winds
• C. A region of high pressure
• D. A weather phenomenon involving tides

Answer: (A)

The main idea is the boundary where two air masses meet. In meteorology, that boundary is called a front—the zone where air masses with different temperatures and humidity interact and weather effects can develop. Among the options, describing the boundary itself as a boundary between air masses aligns with the concept of a front, since it focuses on the separation line between unlike air masses. The other choices point to phenomena that are not the boundary between air masses—storms driven by winds, a high-pressure area, or tides.