Answer: Global organizational markets.
Step-by-step explanation:
In Organizational markets, the main participants are huge trading Institutions such as Governments or large Corporations. In Organizational markets, the participants may be few but the transactions can have a lot of Quantity i.e a government can buy a huge order from one company.
The goods sold here can be highly specialized and made for few buyers and so is not for personal Consumption.
The US buying a drug for anthrax which is a rare disease but can be weaponized shows that this is a specific purchase therefore it is more likely to be a purchase on the Global Organizational Market.