Answer:
A) any means.
Step-by-step explanation:
Contracts for International Sale of Goods (CISG) is a UN sponsored convention similar to the American UCC that regulates international trade of goods between the countries that have ratified the CIGS convention.
The US ratified the CIGS convention in 1988 and Canada did it in 1991.
According to CISG rules, a contract for a sale can be oral or unsigned, but in US courts the UCC will generally prevail.