A person X was driving in a place where all roads ran either north-south or east-west, forming a grid. Roads are at a distance of 1 km from each other in a parallel. He started at the intersection of two roads, drove 3 km north, 3 km west and 4 km south. Which further route could bring him back to his starting point, if the same route is not repeated?
(a) 3 km east, then 2 km south
(b) 3 km east, then 1 km north
(c) 1 km north, then 2 km west
(d) 3 km south, then 1 km north