To determine her power usage, Debra divides up her day into three parts: morning, aftemoon, and evening. She then measures her power usage at 3 randomly selected times during each part of the day What type of sampling is used? A. Convenience sampling B. Simple random sampling C. Systematic sampling D. Stratified sampling

D. Stratified sampling

Step-by-step explanation:

Stratified sampling is a sampling method where the population is divided into subgroups and data is sampled randomly at each subgroup proportional to the size of the subgroups.

Then all sampled data is combined to create the population sample for the study.

Debra collected 9 power usage data, 3 random power usage data from each 3 subgroups: power morning, aftemoon, and evening power usage. She performs stratified sampling method.