Answer: Random
To answer this question, let us first define what Random Sampling is.
Random Sampling describes when every elemnt in a population has an equal chance of being chosen for the sample.
There are 4 types of Random Sampling, but we are going to focus on one type which is the Systematic Random Sampling.
Systematic Random Sampling is a common technique where sample every kth element. For example, surveying every 100th person that walks in a mall.
Now based on the question, it is stated that "You select every 25th student in all the classes". This is an example of Systematic Random Sampling.
Therefore this survey is classified as Random.
