Which of the following are the like fractions?

1. $\dfrac{2}{3}, \dfrac{2}{5}, \dfrac{2}{7}, \dfrac{2}{9}$

2. $\dfrac{2}{3}, \dfrac{3}{4}, \dfrac{4}{5}, \dfrac{5}{6}$

3. $\dfrac{1}{5}, \dfrac{2}{5}, \dfrac{3}{5}, \dfrac{4}{5}$

4. none of these

Like fractions are fractions that have the same denominator.

In option 3,

$\dfrac{1}{5}, \dfrac{2}{5}, \dfrac{3}{5}, \dfrac{4}{5}$

Denominators = 5, 5, 5 and 5

All denominators are same.

So, they are like fractions.

Hence, option 3 is the correct option.