What is an irony mentioned in the passage?

• A. Most of the corn and soybean shipments become feed for chickens and cows so they can be certified organic under US Department of Agriculture guidelines.
• B. Rising consumer demand in what’s been a niche market is creating shortages, pushing companies that supply farms needing organic feed to seek out foreign sources.
• C. Imports such as corn from Romania and soybeans from India are booming, according to an analysis of US trade data released Wednesday by the Organic Trade Association.
• D. Organic poultry and dairy operators shun feed made with seeds from domestic suppliers in favor of foreign products even as the US remains the world’s top grower of corn and soybeans.