单选题 Three salespeople are paid commissions in proportion to the amount of their sales，which total $25，000， $40，000， and$60，000， respectively． If a total of$20，000 is allocated for these three commission，what is the amount of the largest commission paid?
A. $8，000 B. $8，400
C. $9，600 D. $10，000
E. $12，000