Which type of eye movement is primarily executed by the lateral rectus muscle?

The lateral rectus muscle is primarily responsible for the movement of the eye away from the midline of the body, which is defined as abduction. When the lateral rectus contracts, it pulls the eye laterally, allowing the eye to move laterally outward. This is crucial for peripheral vision and tracking objects that are to the side.

In contrast, adduction refers to the movement of the eye towards the midline, which is not the function of the lateral rectus muscle but rather the responsibility of other muscles like the medial rectus. Elevation and depression involve vertical movements of the eye, which are controlled by different muscles. Therefore, the lateral rectus's specific action of facilitating the outward movement of the eye substantiates why the correct choice is abduction.