单选题：We have 4 tapes for 3-way external merge sorting. How shall we d
We have 4 tapes for 3-way external merge sorting. How shall we distribute 31 runs into 3 tapes, such that the total number of passes is minimized.
A.13 runs on Tape 1, 11 runs on Tape 2, and 7 runs on Tape 3.
B.11 runs on Tape 1, 10 runs on Tape 2, and 10 runs on Tape 3.
C.13 runs on Tape 1, 10 runs on Tape 2, and 8 runs on Tape 3.
D.15 runs on Tape 1, 9 runs on Tape 2, and 7 runs on Tape 3.
答案：A
A.13 runs on Tape 1, 11 runs on Tape 2, and 7 runs on Tape 3.
B.11 runs on Tape 1, 10 runs on Tape 2, and 10 runs on Tape 3.
C.13 runs on Tape 1, 10 runs on Tape 2, and 8 runs on Tape 3.
D.15 runs on Tape 1, 9 runs on Tape 2, and 7 runs on Tape 3.
答案：A