The correct option is D Overcrowded roads
From the given options, industrialisation and overcrowded roads are the factors responsible for traffic congestion in cities. The demand for vehicles have been increasing as automobile companies have increased production and decreased the price. As a result, vehicles have become more affordable and sales have increased. It leads to congestion on the road. With many people migrating to cities in search of livelihood, the traffic density has increased leading to congestion of city roads.