This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
The Y-axis is also known as growth axis because 
Select and explain. 
A. Its axis is parallel to patient's growth in height, B. It is an indicator of the direction of growth pattern, C. It is an indicator of the amount of facial growth, D. It increases in size as the growth increases
B: It is an indicator of the direction of growth pattern
Answer: B: It is an indicator of the direction of growth pattern 
Explanation: Y-axis
It is also called as growth-axis angle, measured as the posterior inferior angle on S–Gn–FHP. The Y-axis indicates the degree of downward and forward position of the chin in relation to the upper face. A large Y-axis is indicative of the clockwise rotation of the mandible. Y-axis does not give an indication of the size of the lower jaw but the direction in which it is growing. Mean 59.4°, range 53°–66°.