Which is the correct meaning of introduced as it is used in the sentence?

Alice Watkins had been the middle school soccer coach for ten years. She had developed a great relationship with the players. She loved the excitement of the first practice, the nerves at a big game, and her pep talks in the locker room.
This season introduced a new challenge very different from past seasons, however. As a result of an illness that prevented her from working, she had to take a leave of absence from coaching. Another coach was hired to fill in, but the players missed Coach Watkins. Ms. Watkins told them not to worry. She promised that if they made it to the championship game she would be there to see them play. With that to look forward to, the team worked hard. They made it to the championships. When she heard this news, she was determined to get better in time for the game.
On the day of the big game, Coach Watkins delivered on her promise to be there for her team. She hugged the players and told them to gather around. She wanted to talk to them before the big game. The locker room buzzed with excitement, like a crowd waiting for their favorite band to take the stage. They couldn’t wait to hear from her. Ms. Watkins, too, was excited as she began to speak. She felt like she had to cram a whole season’s worth of pep talks into five minutes since she had missed so much time with them. The players laughed. They told her they had been hearing her usual words of encouragement in their heads all season. It was like she had been with them all along.