If a continuous cable 10 meters long was marked off at intervals of 1/3 meter and also 1/7 meter, and then if the cable were cut at each mark, how many different size length of cable would result?  Choose the correct choice from the following answers:
A) 1	B) 2	C) 3	D) 4	E) 5
In this particular example length (10 meter) is just extraneous information.   The location of the marks for 1/3 meter would be 7/21, 14/21, 21/21, etc...   The location of the marks for 1/7 meter would be 3/21, 6/21, 9/21, 12/21, 15/21, 18/21, 21/21, etc...   The distances between marks are 3/21, 1/21, and 2/21.   The answer is 3.
<result>C</result>
If a continuous cable 10 meters long was marked off at intervals of 1/3 meter and also 1/7 meter, and then if the cable were cut at each mark, how many different size length of cable would result?