The answer is: focus group
Focus groups will consist of small group of people from a certain demographic that is targeted by the marketing team as their sales destination.
Marketing group will collect the focus group in order to know the public's general/unbiased opinion about their products. After collecting the information from the focus group, they will propose some changes to the management team in order to make their products become more appealing.
The answer is A. a single Slavic Group
The reason being is the most people in Europe speak Russian which falls into the Slavic category
The people who take part in research studies are called participants.