Answer:
(C)

Explanation:
On the dot plot there are:
- 2 dots on twelve and one-fourth,
- 7 dots on twelve and half,
- 5 dots on twelve and three-fourths,
- 5 dots on 13 and
- 4 dots on thirteen and one-fourth is given.
Length of String Used Most = twelve and half
Length of String Used Least = twelve and one-fourth
Therefore, the difference in Length

The correct option is C.