A steel company will commend three model workers on May Day. The candidates for the six branches are: Wang from the first company, Qian from the second company, Zhu from the third company, Wu from the fourth company, and Lu from the fifth company. Qi from the sixth company. Company decides to choose one from the first or third company; choose one from the second or fifth company; and neither of the two candidates from the third and fifth companies can be selected at the same time as the second company's candidates.
not selected, which of the following candidates must be selected at the same time?
Qian and Qi