Question 263109
4/12=1/3
6/12=1/2
8/12=3/4
3/12=1/4
the string needs to be between 3 ft and 3 6/12 ft
so A and E are too short 
B too long
D too short
which leaves C which is a the extreme length of 6 inches
A. 3 feet too short
B. 3 ¾ feet 3/4=9/12 too short
C. 3 ½ feet 1/2=6/12 ok
D. 3 ¼ feet 1/4=3/12 tooo short
E. 2 ½ feet too short