Final answer:
The Left Posterior Oblique (LPO) position is the most effective in moving the gallbladder away from the vertebrae in an asthenic patient.
Step-by-step explanation:
The position that will most effectively move the gallbladder away from the vertebrae in an asthenic patient is the Left Posterior Oblique (LPO) position. When a patient is placed in the LPO position, the liver and gallbladder are projected farther from the spine due to the effects of gravity and the natural anatomical orientation of these organs. This positioning helps in obtaining clearer imaging or for surgical access, as it separates the gallbladder from the vertebrae and reduces the overlapping of anatomical structures.