A country intends to import several of the six crops of A, B, C, D, E, and F for use in the country's huge animal feed industry. Taking into account that some crops may contain prohibited ingredients, and their complementarity or potential Substitution and other factors, the country has the following requirements for the import of these crops: (1) All of them do not contain prohibited ingredients; (2) If A or B contains prohibited ingredients, import E and F; (3) If C contains prohibited ingredients Ingredients, then D will not be imported; (4) If you import E, you will import B and D; (5) If you do not import D, you will import C; if you import C, you will not import D.
country?
A,E,F