Final answer:
The term for observing an individual for a set amount of time at different points is known as a time sample, a structured observational study technique. The correct option is d. A time sample.
Step-by-step explanation:
The type of observation in which an individual is observed for a predetermined amount of time, such as 10 minutes observing a classroom, three times during the day, is called a time sample. This method of observation is part of a broader category of research known as observational studies. Observational studies involve measuring characteristics in a sample without attempting to manipulate or control the variables of interest. They can provide valuable insights into behavior and phenomena as they naturally occur. In the context of classroom observation, time sampling allows for snapshots of behavior within set intervals, providing a structured approach to observation.