Which muscle is primarily involved in hip extension and lateral rotation?

The gluteus maximus is primarily involved in hip extension and lateral rotation, making it the correct answer. This muscle is the largest and most powerful extensor of the hip joint and plays a crucial role in movements such as standing up from a seated position, climbing stairs, and running. During activities that require the hip to extend, such as pushing off the ground, the gluteus maximus contracts to pull the thigh backward, facilitating movement.

Additionally, the gluteus maximus contributes to lateral rotation of the hip, which is significant when performing actions that require turning the leg outward. This function is essential in various athletic movements and helps stabilize the pelvis during dynamic activities.

In contrast, while the hamstrings also assist with hip extension, their primary role is as knee flexors, and they do not provide the same level of lateral rotation compared to the gluteus maximus. The biceps and transversus abdominis are not directly involved in hip extension; the biceps primarily function in flexing the elbow and supinating the forearm, while the transversus abdominis plays a critical role in stabilizing the core rather than in hip movements.