Step-by-step Solution:

Step 1: Define the original fraction and express the changes
Let the original fraction be x/y. When the numerator is increased by 25%, the new numerator becomes 1.25x. When the denominator is decreased by 20%, the new denominator becomes 0.8y.

Step 2: Set up the equation
The new value of the fraction is given as 5/4. So, we can write the equation:
\[
\frac{1.25x}{0.8y} = \frac{5}{4}
\]

Step 3: Solve for the original fraction
Rearrange the equation to find \(\frac{x}{y}\):
\[
\frac{x}{y} = \frac{5}{4} \times \frac{0.8}{1.25} = \frac{5}{4} \times \frac{4}{5} = \frac{4}{5}
\]

Answer:
The original value of the fraction is (B) \(\frac{4}{5}\).