Final answer:
William Penn allowed different religions in Pennsylvania due to his own experience of religious persecution in England and to fulfill his vision of a colony with religious tolerance, which was mainly Quaker but welcomed all Christians to participate in its growth.
Step-by-step explanation:
The reason William Penn allowed people to practice different religions in his colony of Pennsylvania was because he had faced persecution for his own Quaker beliefs in England. Penn looked at Pennsylvania as a holy experiment, wanting it to serve as an example to other nations for religious tolerance and social equality. His emphasis on religious freedom attracted many Quakers, as well as persecuted people from other denominations, to Pennsylvania. However, only Christians were permitted to participate in its government. Penn's vision of a colony offering religious tolerance was also a part of fulfilling his commercial interests, acknowledging the value of attracting settlers to the land he governed.
In terms of the predominant religion in Pennsylvania, the answer would be A. Quakerism. The colony was founded primarily for Quaker settlers and was known for its Quaker principles, even though it welcomed individuals of various Christian backgrounds.