My guess (and I didn’t read the rest of the comments): There will be an output of 1 only if A,B,C is 1. If any of A,B or C is 0, the AND gates at the left won’t activate no matter what D does.

A series of mechanical logic gates are 3D printed using the Large Area Projection Microstereolithography (LAPµSL) method. In a Venusian rover, Pascall said scientists could build controls so if ...