Final answer:
The cylindrical - wide weight-bearing surface is the preferable shape for better pressure distribution.
Step-by-step explanation:
The preferable type of residual limb shape for better pressure distribution is a cylindrical - wide weight-bearing surface. This shape allows for a larger contact area between the limb and the prosthesis, which helps distribute the pressure more evenly. The other options, including a conical shape, irregular shape, and flat shape, do not provide the same level of pressure distribution.