A student organization wanted to study voting preferences in its student body during the 2012 presidential election. they selected 120 students at random from each class, freshmen through seniors. the sampling technique being used is:

This is just the basic random sampling. 120 students were chosen at random from all classes and every student had the same chances of getting chosen. Things like social background or race were not taken as a criteria for getting chosen, nor did things like gender. Everyone was chosen at random.