I have been driving for sometime now and haven't really taken time to inspect driver's license until today. I noticed that I have a Class D driver's license while my sister had a Class B driver's license. When we asked the driving school that helped process the driver's license, they responded that men get class D while women get Class B. I have since then confirmrd from my friends and it seems to check so far.

The question now is, what is the reason for the segregation?