Answer:
(C) They are the same
Step-by-step explanation:
The coefficient of variation CV is given by the following formula:

In which
is the standard deviation and
is the mean.
Bob's weight has a mean of 200 pounds with a standard deviation of 16 pounds
This means that
.
So his coefficient of variation is

Mary's weight has a mean of 125 pounds with a standard deviation of 10 pounds.
This means that 
So her coefficient of variation is

They have the same coefficient of variation, so the correct answer is.
(C) They are the same