Question $18$

Which of the following regular expressions means to match any line containing a single$-$digit even number, followed by a single$-$digit odd number, followed by $1$ or more r$\text{'}$s$?$

For example, the following lines would all match:

$-$ The password is $72r.$

$-94rrrrrr$

$-56rr$ is the model of the printer.

$\text{'}[02468][13579]$r$\text{'}$

$\text{'}[02468]*[13579]*$r$+\text{'}$

$\text{'}(02468)(13579)$r$?$

$\text{'}[02468][13579]$r$+\text{'}$