In accordance with the pressure gradient a. air is less tightly packed in high pressure zones and moves away from low pressure zones. b. air is more tightly packed in high pressure zones and moves away from low pressure zones c. air is more tightly packed in high pressure zones and moves toward low pressure zones. d. air is less tightly packed in high pressure zones and moves toward low pressure zones.

b. air is more tightly packed in high pressure zones and moves away from low pressure zones

Explanation:

Pressure gradient is of  describes as the change of the atmospheric pressure to the horizontal distance covered.

It is a dimentional quantity as it expresses in Pascal/meter.

Pressure gradient results in force which is directed from high to low pressure and due to such applied pressure the air is tightly packed.

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.