Final answer:
Mary's condition of a posterior pelvic tilt and hyper-kyphosis is typically characterized by c) tight hamstrings and weak quadriceps due to the pelvic tilt, and weak back extensors associated with excessive thoracic spine curvature.
Step-by-step explanation:
The question concerns Mary, who has a posterior pelvic tilt and a hyper-kyphosis in her thoracic spine. To determine which muscle imbalances best describe her condition, we need to understand the implication of these postures. A posterior pelvic tilt often involves tight hamstrings and weak hip flexors, as the pelvis is pulled into a backward rotation. Hyper-kyphosis, or an excessive curvature in the thoracic spine, typically involves weak back extensors that are unable to maintain an upright posture against gravity, in addition to tight chest muscles that contribute to pulling the shoulders forward.
Therefore, the correct answer to which muscle imbalances best describe Mary's condition would be tight hamstrings and weak quadriceps which are often associated with a posterior pelvic tilt, and weak back extensors that relate to hyper-kyphosis.
Hence, the correct answer is Option C.