Answer:
B. based on information about ones preference and that of others.
C. a way to help an individual focus on best choices when deciding what to watch or buy.
Step-by-step explanation:
Collaborative filtering is the process of filtering or evaluating items for a user based might like based on reactions or opinions by similar users. Information is usually gathered from a lot of users online and used to create a personalized ranked list for the user.
Therefore information about ones preference and that of others and helping an individual focus on best choices when deciding what to watch or buy are good examples of the usage of collaborative filtering technique.