Answer:
The sampling technique applied in this case is known as stratified random sampling.
Step-by-step explanation:
Stratified random sampling involves dividing the population into distinct groups or strata based on certain characteristics, and then randomly selecting samples from each stratum. In this scenario, the student council divided the population of students into four strata: freshmen, sophomores, juniors, and seniors. They then took random samples of 25 students from each stratum.
By using stratified random sampling, the student council ensured that their sample represented the different grade levels proportionately. This technique helps to ensure that each group is adequately represented in the sample, which can provide a more accurate representation of the overall student population's opinions or characteristics.