What do closely spaced isobars on a weather map indicate?

Closely spaced isobars on a weather map indicate areas of significant pressure change over a short distance. This is indicative of strong gradients in atmospheric pressure which translates to fast wind speeds. When isobars are packed closely together, it shows that the difference in pressure between adjacent areas is larger, leading to more forceful winds as air moves swiftly from high pressure to low pressure regions. Thus, the correct choice effectively reflects the relationship between pressure differences and wind speed, making it clear that closely spaced isobars signify faster winds.