The wind is described as geostrophic when:

A The pressure gradient force balances the centripetal force.

B Winds blow in a straight line parallel to contour lines on a weather map

C The pressure gradient and Coriolis forces act on the air in the same direction.

D Winds blow under the influence of only the pressure gradient force.

B Winds blow in a straight line parallel to contour lines on a weather map

Explanation:

Geostrophic Wind -

It is the pattern of the wind, when the flow of wind is exactly parallel to the contour lines of the weather map.

It is a theoretical wind which results from the balance between the pressure gradient force and the Coriolis force.

Hence, the correct description for the Geostrophic Wind is option (b).