Why Does the Government's Role of Enforcing Contracts Facilitate Exchange

Why does the government's role of enforcing contracts facilitate exchange?

A) Enforcing contracts allows people to trade with confidence that the contracts they enter will be met.
B) Enforcing contracts guarantees consumers that the government will bail them out in case the seller does not fulfill his end of the contract.
C) Enforcing contracts guarantees sellers that the government will bail them out in case the buyer does not fulfill his end of the contract.
D) Enforcing the contract effectively makes the government the seller's partner in the business.