A clerk spent his 35-hour workweek as follows: 1/5 of his time in sorting mail; 1/2 of his time in filing letters; and 1/7 of his time in reception work. The rest of his time was devoted to messenger work. The percentage of time spent on messenger work by the clerk during the week was most nearly:
A 6%
B 14%
C 10%
D 16%