Final answer:
The hamstrings are likely pulling in the posterior direction when the rectus abdominis muscle pulls the anterior portion of the pelvis in a superior direction to produce a posterior tilt of the pelvis.
Step-by-step explanation:
If the rectus abdominis muscle is pulling the anterior portion of the pelvis in a superior direction to produce a posterior tilt (rotation) of the pelvis, the hamstrings are most likely pulling in the posterior direction.
The hamstrings, a group of posterior thigh muscles, are attached to the ischial tuberosity of the pelvis and run down to the bones of the lower leg. When the hamstrings contract, they generally pull the pelvis in a posteroinferior direction, complementing the action of the rectus abdominis during the posterior pelvic tilt.