Identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.
The author surveyed a sample from the population of his statistics class by
identifying groups of males and females, then randomly selecting five students from each ofthose two groups.

Stratified sampling

Step-by-step explanation:

Random sampling : Researcher selects individuals randomly for sample.Systematic sampling :  Researcher follows a periodic interval to select individual from population.Convenience sampling :  Researcher selects individuals randomly according to his convenience.Stratified sampling : Researcher splits the population into groups ( known as strata) and then selects individuals from each strata.Cluster sampling : Researcher splits the population into groups ( known as clusters) and then selects clusters randomly for sample.

Here, The author surveyed a sample from the population of his statistics class by identifying groups of males and females.

Since he randomly selecting five students from each of those two groups.

I.e. Groups of males and females are strata and author selected participants for sample from each strata.

Therefore , the sampling technique he used = Stratified sampling .