Which of these options describes a feature of a varifocal lens?

A varifocal lens is specifically designed to have adjustable focal lengths, allowing the user to zoom in and out within a certain range of focus. This feature enables the lens to be versatile in capturing images at varying distances without the need for changing lenses. By adjusting the focal length, photographers or videographers can achieve different compositions and perspectives, making the varifocal lens highly useful in dynamic shooting environments where versatility is important.

In contrast, interchangeable lenses refer to the capability to swap out different lenses on a camera body, which is a characteristic of modular camera systems rather than a feature inherent to varifocal lenses themselves. Built-in autofocus is a feature that some lenses may offer, but not all varifocal lenses are equipped with this capability. A fixed aperture size would imply that the lens cannot adjust its opening to allow more or less light, which is different from the adaptive functionality found in many varifocal lenses that might offer variable apertures.