Which of these statements best defines a stratified random sample? It is a sample where every nth element of the population is selected in a sequence.

It is a sample where the population is first broken into groups and then elements are randomly selected, in proportion, from each group.

It is a sample where the population is divided into roughly equal groups, and then elements are randomly selected from each group.

It is a sample in which every element has the same chance of being selected from the total population.