Jill examines the career interest of children of international diplomats. She selects the children of international diplomats from the United States who were in service between 1980 and 1990. The children had to be at least eight years old but less than 16 at the time of their parent's service and had to be stationed outside the United States with their diplomat parent for at least 24 continuous months. Jill is using which type of sampling?
◦ Homogeneous sampling
◦ Snowball sampling
◦ Intensity sampling
◦ Random purposive sampling