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

Convenience sampling is a non-random method that takes whoever is easiest to reach.

Stratified random sampling randomizes within strata and is a probability method.

Simple random sampling gives every unit an equal, independent chance and is random.

Cluster random sampling randomly draws whole groups and is a probability method.

Convenience samples carry high bias because participation depends on accessibility.

Their findings usually cannot be generalized to the wider population.