Using sampling concepts, it is found that the correct option is:
b. The 9000 registered voters from California in the database.
Example of sampling, involving sample and population:
I survey 1000 randomly selected residents of New York State, asking if they are Buffalo Bills fans or not.
In this problem, 1000 registered voters in California are randomly selected from the database and asked their opinion, hence:
A similar problem is given at https://brainly.com/question/13852073