If the goal of the research was to provide a demographic and lifestyle profile of a heavy user of a product, then the preferred type of research would be .

Qualitative research.

Explanation:

As the exercise suggests, the qualitative research provides a demographic and lifestyle profile of a heavy user of a product. It's a method of observation and analysis, whose purpose is to gather non numerical information in order to understand or predict how often a certain phenomenon happens.

answer; ///any two strangers are likely to share many coincidental similarities;

i believe the answer is: description

description refers to the goal of psychologist to identify the phenomenon that being observed. this goal is being actualized by collecting data/information from various clues that observed through the phenomenon. this goal must be accomplished before pyschologist able to create methods of treatment.