Question

which phrase defines altitude?
how tightly molecules are packed
a column of air pushing on an area
the force pushing on an area or a surface
the height of a given point above sea level

Explanation:

• "How tightly molecules are packed" defines density, not altitude.
• "A column of air pushing on an area" describes air pressure.
• "The force pushing on an area or a surface" defines pressure in general.
• "The height of a given point above sea level" is the standard definition of altitude.

Answer:

D. the height of a given point above sea level