Zippers, Corp., a development company, has constructed a zip-line course on government land after signing a leasing agreement with the state government. A few years after signing the agreement, the state authority sanctioned the Never-ending Tunnel Company to build a long tunnel through the land where the zip-line course already exists. The proprietors of Zippers, Corp. claim that the state authority has violated their existing agreement. Which of the following is most likely to be applied in this case between Zippers, Corp. and the state government? a. the free exercise clause
b. the contract clause
c. the doctrine of preemption
d. the establishment clause
e. the commerce clause