Which of the following is correct?

Question 5 options:

a. A contract that does not provide a specific price for goods will never be enforceable.

b. If a contract does not specify a price but provides for an external market factor to determine this, the contract will likely be enforceable.

c. A prudent buyer will request a pro forma or sample invoice to ensure that all the buyer's import and customs regulations are adhered to.

d. Only (a) and (b) are correct.