The Japanese Manufacture Tractors for Rice Paddies

The Japanese manufacture tractors for rice paddies.They are smaller than most U.S.tractors and perfect for a weekend farmer who wants to tend to a small garden.The tractors are not sold in the U.S.through any authorized channels, yet they are available in the U.S.at prices below the manufacturer's suggested retail price.What is the term for how these tractors are being sold?

A) on the gray market
B) under the counter
C) over the counter
D) through globalized channels
E) through a distribution monopoly