Pls help with this problem!

Mcdonald's runs two business models. Some Mcdonald's restaurants are wholly-owned and operated by the main parent company, while some Mcdonald's restaurants follow a franchise model i.e. the main parent company charges a franchise fee and the restaurant is then independently owned and operated by the franchise owner. Empirical evidence suggests that Mcdonald's restaurants that are wholly-owned by the parent company (the first type described above) charge lower prices than the prices charged by independent franchises (the second type described above). How can this difference in prices charged be explained