Final answer:
Posterior thoracic muscles that move the pectoral girdle include the rhomboids, which are correctly identified in option C). The deltoid and pectoralis major move the humerus and are not the correct answer in this context.
Step-by-step explanation:
The posterior thoracic muscles that move the pectoral girdle are the trapezius, levator scapulae, rhomboid major, and rhomboid minor. Among the options provided, option C) Rhomboids correctly represents the posterior thoracic muscles involved in the movement of the pectoral girdle. These muscles act to move the scapula, which forms part of the pectoral girdle, while muscles such as the deltoid and pectoralis major, which are also mentioned, move the humerus.