How did Yuehua selected their trainees?

During the start of BP, when the Yuehua trainees were revealed for the first time, I saw an old comment here stating that the Chinese trainees were selected based on their potential appeal to kfans, which I guess is true for Hao since he definitely fits the korean beauty standards.

This made me wonder, how did Yuehua selected the trainees that will participate in BP. Were they the most-debut ready during that time? Or do you think the trainees they sent were already a formed group and they sent them to BP for a pre-debut publicity?

Nonetheless, Yuehua struck gold with their trainees. Who would have imagined that they would be able to defeat Mnet's ass and make four of their trainees debut, with one of them even securing the center position.