Final answer:
While none of the positions listed inherently carry a great risk of postural hypotension, standing from the supine or lithotomy positions may cause this issue since the body has to adjust and keep blood pumping against gravity.
Step-by-step explanation:
The risk of postural hypotension, or a sudden drop in blood pressure upon changing positions, is the greatest when transitioning from a lying or seated position to standing. Specifically, the question asks about which position might inherently carry the greatest risk, not the transition itself. While lying in a supine position (A) or a prone position (D) typically does not involve this risk, standing up from these positions might. The Trendelenburg position (B), where the head is lower than the feet, generally would not cause postural hypotension upon standing because the head is already in a lower position, promoting blood flow to the brain. The lithotomy position (C), where the legs are raised and separated, may carry some risk; upon returning to a standing position from the lithotomy, gravity can pull blood into the lower extremities, potentially causing postural hypotension. However, this risk usually arises when moving to an upright position, not while maintaining the lithotomy position itself. Therefore, none of the positions listed inherently carry a great risk of postural hypotension while the person remains in that position.