Answer: Option 'E' is correct.
Step-by-step explanation:
Since we have given that
If the length of one piece of rope is 2.8 meters shorter than the length of the other.
Let the length of first piece be 'x'.
Let the length of second piece be 'x-2.8'
Total length of rope = 20.6
So, According to question, it becomes,
[tex]x+x-2.8=20.6\\\\2x=20.6+2.8\\\\2x=23.4\\\\x=\dfrac{23.4}{2}\\\\x=11.7[/tex]
So, the greatest number of the length of part of rope is 11.7 m.
Hence, Option 'E' is correct.