Answer:
C. Stratified Sampling
Step-by-step explanation:
Based on the information provided within the question it can be said that the sampling method that is being used in this scenario is called Stratified Sampling. This method refers to when a researcher divides a population into various different groups and then chose a predefined number of samples at random from each group. Which is exactly what is happening in this scenario since Carrie divided her day into three parts (groups) and measured her mood twice at random for each part of the day (group).