Context: The passage below describes an experiment.

Josiah and his friend Marie flew nylon kites on the beach. They wondered if putting a tail on a kite would affect how well the kite flew.
Josiah flew a kite that did not have a tail for five minutes. Then, he attached a four-foot-long tail and flew the kite for five more minutes. Josiah repeated this with three similar kites, alternating whether he started the kite with or without a tail. During each flight, Marie counted the number of times the kite crashed to the ground.
Figure: flying a kite.
In this experiment, which were part of a control group?
A. the kites with tails
B. the kites without tails
Determine the correct option from the provided choices and reply with its corresponding letter.

B