Hershey's Special Dark is a component of the traditional Hershey's Miniatures assortment first sold in 1939, when the Special Dark was called Semi-Sweet.

When did hershey's special dark come out? Okie... think carefully first, then make a decision:
The relevant sentence in the passage is: Hershey's Special Dark is a component of the traditional Hershey's Miniatures assortment first sold in 1939, when the Special Dark was called Semi-Sweet. So, the answer is 1939.