Reese's Peanut Butter Cups are produced by The Hershey Company.
H. B. Reese created the candy in 1928 after founding the H. B. Reese Candy Company in Hershey, Pennsylvania. Reese had previously worked at a Hershey dairy farm and used Hershey chocolate in his early confectionery products. The original cups combined a peanut-butter center with a chocolate coating, an unusual pairing that became his most successful product.
The H. B. Reese Candy Company merged with the Hershey Chocolate Corporation in 1963. Reese's remained a distinct brand, but production and ownership became part of Hershey. That history explains why the answer is sometimes casually given as “Reese's” or “Hershey's”; the quiz's company-level answer is Hershey, formally The Hershey Company.
Reese's Peanut Butter Cups became Hershey's top-selling product in 1969. They are also related to other Reese's products, including Reese's Pieces and the Take 5 bar, but those products should not be confused with the original cup.