Which muscle extends from the thorax to the pubis?

The rectus abdominis is the correct choice as it is the muscle that runs vertically along the front of the abdomen, extending from the thorax (specifically from the xiphoid process of the sternum) down to the pubis. This muscle plays a crucial role in stabilizing the core, supporting the spine, and facilitating movements such as trunk flexion and pelvic tilt. Its structure is characterized by tendinous intersections that create the "six-pack" appearance in well-defined abdominal muscles.

In contrast, the obliques are located on the sides of the abdomen and provide twisting and bending motions but do not extend vertically from the thorax to the pubis. The latissimus dorsi is a large muscle that extends from the lower back to the upper arm, primarily involved in actions like shoulder adduction and extension rather than abdominal support. The transverse abdominis is situated deeper in the abdominal wall, playing a vital role in core stability but does not extend from the thorax to the pubis like the rectus abdominis does.