Which of the following statements regarding thoracolumbar fascia is correct? a. It has more than one layer and the anterior layer covers the anterior surface of the psoas major muscle. b. It has more than one layer and the middle layer goes between the quadratus lumborum and deep back muscles. c. It has more than one layer and the posterior layer covers the anterior surface of the deep back muscles. d. It has one layer and covers the posterior surface of the deep back muscles.