Answer:
B) secondary; primary
Step-by-step explanation:
Secondary data is data collected from other researches. In this age, there is a lot of easily accessible data made available freely or at low cost. Examining them first not only help researchers find needed data cheaply, but also give them ideas about what they could find out from those data (serendipitous discovery).
Primary data is data collected from first-handed sources by the the researchers themselves by methods including surveys, interviews, direct observation, etc. It is costly to obtain so researchers only come to that when they can't find good secondary data for their purposes.