According to the selection, muscle participation in the process of thinking is ______.

A．To tell campus personnel of the new library services.
B．To announce the new movies on campus this summer.
C．To notify university people of important schedule changes.
D．To remind the students to validate their identification cards.

A．is rich in low-grade aluminum-bearing ores
B．is short of aluminum-making techniques
C．has to import ninety percent of its annual need of aluminum
D．has to produce fifty percent of the world's supply to meet its annual aluminum demand