Answer:
The correct answer is D, <em>Cathedrals needed to accommodate the growing practice of pilgrimage to visit holy relics</em>.
Explanation:
During the 11th and 12th centuries there was an increase in the number of pilgrimage voyages in medieval Europe. Many people traveled long roads to visit cathedrals that were believed to possess holy relics, that is objects that had belonged to saints or that were saints' bodies' parts.
When they visited these places they had to be large in order to fit pilgrims and the daily services. Pilgrims would walk around the place stopping to pray in different altars and shrines to different relics or tombs.
The answer for your question is the 3rd answer
The trade union constantly hired unskilled workers in the 1800s
A Slums are NOT an example of positive effects of city growth.
