Four objects that are symmetrical along vertical planes are placed in four containers in the orientation shown below. Molten wax is poured in each of these containers up to the level indicated on the objects. Assuming that wax does not stick to the objects, which of the objects will leave its exact negative impression on the set wax when they are vertically lifted?
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A horizontal cylinder submerged exactly to its center forms a draft-neutral semi-cylinder that is always moldable. However, if submerged even slightly above its center, it immediately creates an undercut.
Step 1: Check for undercuts. A clean negative impression releases only if the object has no undercuts that would lock it in the solidified wax. Step 2: Pick the moldable shape. Only one object can be drawn straight up without trapping; that is the answer. \[ \boxed{\text{Option 1 (Fig A)}} \]
