Which of the following is NOT a type of North used in navigation?

Relative North is not classified as a type of North used in navigation. In navigation, True North refers to the direction along the Earth's surface towards the geographic North Pole. Magnetic North indicates the direction a compass points, which can vary from True North due to the Earth's magnetic field. Grid North is a concept used in map reading, where it refers to the direction of north as indicated on a specific grid system, such as UTM (Universal Transverse Mercator). Each of these types serves distinct purposes in navigation and map reading, while Relative North generally refers to the direction of north from the observer's current position, which can vary and is not commonly used as an established navigational reference.