The number line that best models the expression 3 divided by 1/3 is C.
Here's why:
Dividing by a fraction is the same as multiplying by the reciprocal of that fraction. The reciprocal of 1/3 is 3.
Therefore, dividing 3 by 1/3 is the same as multiplying 3 by 3.
Multiplying 3 by 3 gives us 9.
So, the answer we're looking for is the number line that goes from 0 to 9 with increments of 1.
Number line C in the image you sent matches this description. It starts at 0 and ends at 9, with equally spaced increments of 1.
Therefore, it is the best model for the expression 3 divided by 1/3.