An Islamic survey conducted by the Gallup organization consisted of a random sample of 10,004 people living in 9 predominantly Islamic countries. The sample was collected by interviewers going to people's homes in randomly chosen areas in each of the 9 countries. The population represented by this sample was:
a) all Muslims in the world.
b) all Muslims who live in any Islamic country.
c) all people, Muslim and non-Muslim, living in homes in any of the 9 countries.
d) all people, Muslim and non-Muslim, who live in the same cities and villages as the people in the sample.