Final answer:
To obtain a 7D license, you must hold a regular driver's license for 2 years.
Step-by-step explanation:
In order to obtain a 7D license, which is a class of commercial driver's license (CDL) in Massachusetts, you must hold a regular driver's license for at least 2 years.
After holding your regular driver's license for the required period of time, you can apply for the 7D license, which allows you to operate a school bus or school pupil transport vehicle.
It's important to note that the specific requirements and length of time may vary depending on the state or country you are in, so you should always check with your local Department of Motor Vehicles for accurate information.