The ANZ Bank Is Gathering Information About Average Customer Waiting

The ANZ Bank is gathering information about average customer waiting times. When customers enter a branch, they are given a slip of paper with a unique customer number and a time stamp. The customer hands this to the teller who notes the time of service. By comparing the start time and end time, the Bank is able to determine each customer's waiting time. At the end of a day or a week, the data are aggregated to arrive at average waiting times on a branch by branch basis. The ANZ is engaged in which type of research?

A) experimental research
B) casual research
C) survey method
D) observational research
E) ethnographic research