Discuss what would be the most appropriate QC tool to use to attack each of these problems:

a$.$ A rental car agency is getting numerous complaints about the length of time that customers have to wait to obtain a car. They need to get a better handle on the factors that relate to the wait time. $(1$ mark$)$

b$.$ A kitchen in a restaurant always seems to be getting orders mixed up and plated incorrectly. $(1$ mark$)$

c$.$ A local zoo wants to understand where its guests come from in order to better target marketing efforts. $(1$ marks$)$