Alex was classified as an achievement-oriented leader by his team. Which one of the following would describe Alex's leadership style best? ( )
选项：

A:He lets subordinates know what's expected of them, schedules work to be done, and gives specific guidance on how to accomplish tasks.
B:He shows concern for the needs of his subordinates and is friendly.
C:He sets challenging goals and expects subordinates to perform at their highest level.
D:He consults with subordinates and uses their suggestions before making a decision.