What is a recommended water skiing safety practice?

These are the recommended water skiing safety practice. First, you need to learn how to swim to get out of the water and use the tow rope safely. You also need to have the basic knowledge on the spotter's hand signal. You should ensure that the operator of the boat is licensed and that he has already experience with the boat you will be using and the body of water. You should always use a life jacket approved by the U.S. Coast Guard. You should also make sure that the environment is safe. So, it is better to have water skiing during the day than during the night.

It's definitely not b or c, it's either a or d but i can't figure out which one sorey