The role of feature detectors is to:

Feature detectors are specialized neurons in the brain that respond to specific features of visual stimuli, such as edges, angles, and movements. These neurons are crucial for the initial stages of visual processing as they analyze various aspects of visual inputs and allow the brain to construct a more complex perception from simple shapes.

The reason the chosen answer accurately represents the function of feature detectors is that they are predominantly involved in responding to very basic visual information, like lines of particular orientations (horizontal, vertical, or diagonal). This means that when a horizontal line enters the visual field, specific feature detectors will become activated, sending signals to other areas of the brain for further processing.

In contrast, detecting color stimuli pertains more to the function of cones in the retina, while responding to specific objects like houses involves higher-level cognitive processing that integrates various visual elements, not just simple features. Regulating pupil size is related to the function of muscles controlling the iris and is connected to light adaptation rather than the processing of visual features. Therefore, feature detectors primarily serve the purpose of responding to the most elementary forms of visual stimuli, making the selection of very simple stimuli such as a horizontal line the appropriate choice.