What defines a conformal map's effectiveness?

A conformal map is designed to preserve the shapes of geographic features, regardless of the distortions that might occur in other aspects, such as area or distance. The primary use of conformal mapping is in navigation and in cartography where maintaining the correct angles and shapes of landforms is crucial for accurate representation of the Earth's surface. This means that while the size of areas may not be accurately represented, the overall shape, such as the curvature of coastlines or the outline of countries, remains true to form. This characteristic is especially important for tasks that require precise angular relationships, such as engineering or aviation operations. Therefore, option B accurately describes the effectiveness of a conformal map.