Which of the following is an example of a random sampling method?

Two-stage random sampling is a probability method that randomly selects clusters and then units within them.

Convenience sampling takes whoever is readily available and is non-probability.

Purposive sampling chooses units by the researcher's judgment and is non-probability.

Snowball sampling recruits through referrals and is non-probability.

Both stages of the two-stage design use random selection, keeping it probability based.

It is a common form of multistage sampling used in large national surveys.