Is Mcdonald's coffee robusta or Arabica?

Hello there, I'm curious to know about the coffee served at McDonald's. I've heard that there are two main types of coffee beans used in coffee production - Robusta and Arabica. Could you please enlighten me on which one of these beans McDonald's uses for their coffee, or do they perhaps use a blend of both? I'm really interested in knowing the details behind their coffee sourcing and production process. Thanks in advance for your insight!