Which of the following is true of sampling?

a

It is the process of gathering data from a subset of the total population, rather than from all members of the group.

b

It is a hybrid of primary and secondary research conducted by a research company, spreading the cost across many clients to reduce the price.

c

It refers to the process of identifying what information is needed and how it will be collected.

d

It refers to watching how people behave, either in person or by using a machine to record events.