PK chewing gum, referring to Peppermint and Keep-your-shape gum, was a product of the William Wrigley Jr. Company. While not directly invented by William Wrigley Jr. himself in the sense of formulating the specific recipe from scratch, the gum was produced and marketed under his leadership and company. Therefore, the most accurate answer is that the William Wrigley Jr. Company invented PK chewing gum.
While William Wrigley Jr. didn't personally invent the formula, his vision, marketing genius, and leadership were instrumental in the creation, popularization, and success of PK chewing gum. The company likely employed chemists and flavorists who developed the specific formulation.
Think of it like this: A movie director doesn't invent the camera or write the script, but they are credited with directing the film. Similarly, Wrigley Jr. led the company that conceived, developed, and brought PK chewing gum to the masses.
