Final answer:
In the anterior view from the front, the primary muscle is the pectoralis major, which is central to moving the humerus anteriorly and is visibly located on the anterior thorax.
Step-by-step explanation:
The primary muscle visible in the anterior view from the front is the pectoralis major. This muscle originates from the sternum and the anterior side of the scapula, and it is responsible for moving the humerus anteriorly. When compared to other muscles listed in the question such as the biceps brachii, which performs a bicep curl, and allows the palm of the hand to point toward the body while flexing, the pectoralis major is more anteriorly positioned on the thorax. The other muscles mentioned: rectus abdominis is located in the anterior wall of the abdomen and the quadriceps femoris group is on the anterior thigh, but the pectoralis major stands out as a primary muscle in the anterior view of the upper body.