"why did maryland, a colony founded as a safe haven for catholics, have so many protestants living there by the 1640s? "

The colony of Maryland was indeed founded to be a safe haven for presecuted Catholics.

Since the 1530's when Henvy the VIII broke off from the Roman Catholic Church, many Catholics in the British Empire were seen with suspicion and often presecuted.

George Calvert and his family members established the colony of Maryland to not only turn into a land development investment but aslo help to provide a safe place for Catholics to practice their religion.

However, since the colony of Maryland was a business investment at a strategic location, people from all walks of life began to settle there.

This lead to flaring tensions and by 1649, the Colony was forced to pass a law for religious tolerance, the first of its kind in the colonies.

c is not the correct answer.