Topic: Interchange of Parts of Speech,

Best Answer Explained in Below-:

The correct adjective form of "leader" is indeed "leading" (option D). The term "leading" describes something or someone that is at the forefront or has a guiding role. In a sentence, you might say, "She holds a leading position in the organization," indicating her influential role.

Now let's consider the other options. "Leadership" (option A) is a noun that refers to the action or ability to direct a group or organization. While "lead" (option B) can serve as a verb (“to lead”), it isn't used as an adjective in this context. "Leaderly" (option C) is less common and doesn't have the same established usage or recognition as "leading" in modern English.

Using "leading" effectively conveys the idea of someone being a prominent figure or a primary influencer, which aligns perfectly with the definition of a leader in various contexts, including business and social situations. Thus, "leading" is the most appropriate and widely accepted adjective derived from "leader."