In Singapore, Coca-Cola wanted to develop an advertisement program. They selected a group of teenagers in a room, and a trained moderator facilitated discussion asking questions on brand's image, advertisement, social trends, TV watching habits, and snack usage. This type of research is called:
A) survey research.
B) observational studies.
C) comparison studies.
D) focus group research.
E) experimental research.
Answer: D) focus group research.