The Main Problem with Relying on Contracts to Reduce Opportunistic

The main problem with relying on contracts to reduce opportunistic behavior by alliance partners is that

A) in cross-border alliances, the contracts are often not enforceable due to differences in legal systems.
B) contracts create motivations for rule-evading behavior.
C) contracts are ignored by opportunistic firms because the cost of enforcing the contract is too great for the other partner.
D) it is impossible to specify all opportunistic actions by an alliance partner.