Answer:
Simple Random Sampling
Explanation:
Sampling is the process of drawing a small group of representative people from population.
Random Sampling is when all the units of population have equal chance of being chosen as a sample.
Simple Random sampling is choosing a subset randomly from the entire set.
Researcher recruiting participants for experiment by posting announcement in psychology department, asking for volunteers. It is a simple random sampling as sample is randomly drawn by invitation to volunteer from the population of all people in psychological department.