Final answer:
The type of sampling in this case is stratified random sample.
Step-by-step explanation:
The type of sampling in this case is b. stratified random sample. In a stratified random sample, the population is divided into distinct groups or strata based on certain characteristics, and then a random sample is taken from each stratum. In this case, the manager selected four departments as the strata and conducted interviews with all the employees in those four departments.