This is a tricky question because it is impossible to find the exact values of any of the variables. The best way to find the value of the expression (x – a)/(y – b) is by substitution.

For instance, if x/y = ¼, then 4x = y. Similarly, if a/b = ¼, then 4a = b. Substitute those values into the denominator:

(x – a)/(4x – 4a)

= (x – a)/4(x – a)

= 1/4, choice (C).