Solution :
a). The researcher in the experiment recruited 12 adults wo are healthy to conduct the study. So the individuals are the "healthy adults".
The treatment is the "reading technology" and the response variable in the experiment is the time taken to get a deep sleep.
b). Here, in this research study every participant are randomly assigned to the treatment, i.e. the e-book or the print book at night. So we can say that a true experimental research design has been made to conduct this experiment.
c). It is very important to select the e-reader night or the print book at random order for the participant in order to reduce bias and also to remove any effect of the confounding variable.
The randomization of the participants means the random assignment of the treatments.