Which leaf arrangement is characterized by leaflets arranged along a central axis?

The correct answer focuses on the characteristic structure of a pinnately compound leaf. In this arrangement, the leaflets are distributed along either side of a central stem or axis, which is referred to as the rachis. This configuration allows for an efficient use of sunlight and space, as the leaflets may also move in relation to the sun's position, optimizing photosynthesis.

Pinnate leaves can vary in terms of the number of leaflets, offering a diverse shape that can vary from several small leaflets to fewer, larger ones. This type of leaf arrangement is prevalent in many tree species and herbaceous plants, aiding in their ability to adapt to different environments.

In contrast, whorled arrangements have leaves that grow in a circular pattern around the stem. Palmately compound leaves have leaflets that emanate from a single point at the end of the petiole, resembling fingers extending from the palm of a hand. Alternate leaf arrangements feature individual leaves that grow at different heights along the stem, providing a staggered appearance. Each of these other arrangements showcases different ways that plants have evolved to maximize light capture and space usage, but they do not describe the specific organization characterized by pinnate compound leaves.