When 0.04 is written as a fraction in its simplest form, then the sum of numerator and denominator is

1. 7

2. 21

3. 26

4. 104

$0.04 = \dfrac{4}{100} = \dfrac{1}{25}$

Sum of numerator and denominator = 1 + 25 = 26.

Hence, option 3 is the correct option.