$\dfrac{0}{5}$ is a rational number, $\dfrac{0}{8}$ is a rational number, then $\dfrac{0}{5} ÷ \dfrac{0}{8}$ is:

1. an irrational number

2. a rational number

3. 0

4. undefined

$\dfrac{0}{5} ÷ \dfrac{0}{8}\\[1em] = \dfrac{0}{5} \times \dfrac{8}{0}\\[1em] = \dfrac{0 \times 8}{5 \times 0}\\[1em] = \dfrac{0}{0}\\[1em]$ $\dfrac{0}{0}$ is undefined.

Hence, option 4 is the correct option.