C.  1/10
Step-by-step explanation:
To find the value of a digit in a number, set all the other digits to zero.
 The value of the 5 in 634,952 is 000,050 = 50.
 The value of the 5 in 43,597 is 00,500 = 500.
We want to find the multiplier k such that ...
 50 = k×500 . . . . . . . 50 is "k" times 500
Divide by 500 to see ...
 50/500 = k = 1/10
The value of 5 in the first number is 1/10 times the value of 5 in the second number.