• Holding the option key down while clicking on a path with the Selection tool
(the pointer) selects the entire path.
• Holding the option key while dragging a selected path (using the technique above) drags out a copy of the path. Be sure and release the mouse button before the option key, or the copy won't be created.
• Holding the Option key after placing an origin when rotating, enlarging, reflecting, or shearing, gives you a transformed copy of the original path.