Apressure gradient produces strong winds, but a pressure gradient produces low wind speeds.
(a) little; big
(b) isobars far part; isobars closer together
(c) weak; strong
(d) strong; weak

D. Strong, Weak.

Explanation:

A strong pressure gradient produces strong winds and a low-pressure gradient produces low wind speed. Because wind is simply the air in motion. Flowing from high atmospheric to low atmospheric pressure. A pressure gradient is how fast or low pressure changes over time. So, when pressure gradient changes rapidly over a small area over a period it's said to be of high or strong nature. Thus resulting winds of a high gradient.  The effect of Coriolis force that pushes the winds to the right in the northern hemisphere and left in the southern hemisphere due to the earth's anticlockwise rotation motion.  The pressure is defined by a spatial scale because the pressure changes more rapidly and vertically. Isobars are used to measure these pressure gradient flowing from high to lower gradient on a map. It has originated from Newton's second law of motion.