Read the following article and select the best answer. Article: It was a very foggy day in London. The fog was so thick that it was impossible to see more than a foot or so. Buses, cars and taxis were not able to run and were standing by the side of the road. People were trying to find their way about on foot but were losing their way in the fog. Mr. Smith had a very important meeting at the House of Commons and had to get there but no one could take him. He tried to walk there but found he was quite lost. Suddenly he bumped into a stranger. The stranger asked if he could help him. Mr. Smith said he wanted to get to the Houses of Parliament. The stranger told him he would take him there. Mr. Smith thanked him and they started to walk there. The fog was getting thicker every minute but the stranger had no difficulty in finding the way. He went along one street, turned down another, crossed a square and at last after about half an hour's walk they arrived at the Houses of Parliament. Mr. Smith couldn't understand how the stranger found his way. "It is wonderful," he said. "How do you find the way in the fog?" "It is no trouble at all to me," said the stranger, "I am blind." Question: Why is it no trouble at all to the stranger to find the way in the fog? - Because he is a local inhabitant of London. - Because he lives next to the Houses of Parliament. - Because he is familiar with the route. - Because he finds the way not by sight but by heart.
A:
Because he finds the way not by sight but by heart.