In this question, we are given a specific naming convention for directions. According to the given convention, South-east is called East, North-west is called West, and South-west is called South.
To find out what North is called, we need to follow the same naming convention. Since North-west is called West, and North is in the opposite direction of West, we can conclude that North should be called North-west.
Therefore, option 3, North-west, is the correct answer.
Option 1, East, is incorrect because it corresponds to South-east according to the given naming convention. Option 2, North-east, is incorrect because it does not follow the naming convention given in the question. Option 4, South, is also incorrect as it is not the correct name for the North direction according to the given convention.
Hence, the correct answer is option 3, North-west.