The lack of marketing information about religion is primarily due to select one:
a. the small number of people who are influenced in the marketplace by religious issues
b. the dollar value of the christian market being very low
c. traditional bigotry toward religion
d. religion being somewhat of a taboo subject among researchers

The lack of marketing information about religion is primarily due to religion being somewhat of a taboo subject among researchers

Explanation:

Religious topic has become a topic of taboo and arguments nowadays. These are the days where people are judgmental on the basis of religion and faiths. There are also an inbuilt fear that exists in the minds of the people when they express their convictions and belief because it may lead to a relentless argument and debate.  

So people keep it confined to one’s own self regarding the religious beliefs and faiths. Also there is an apprehension that people may not be accepted socially if they happen to express their religion and faith.