A certain unit seeks external cooperation and is preparing to determine one or several partners in the four units of A, B, C, and D  After careful investigation and discussion, the management of the unit has finally formed the following three opinions: (1) Regarding A and B For the two units of , at most one should be selected  (2) For the two units of A and D, choose at least one  (3) If you choose the C or D unit, you cannot choose the B unit
In the final decision, the unit leader only adopted the above one
Choose A, B, D