Soul Surfer

In 2003, teenager Bethany Hamilton lives in Kauai, Hawaii with her parents Tom and Cheri, and two brothers, Noah and Timmy. All are surfers, but she and her best friend Alana Blanchard have grown up with a passion for the sport and enter a competition. Her church youth ministry leader, Sarah Hill, is disappointed when she has to withdraw from a planned mission trip to Mexico because of the contest.
In the competition, Bethany and Alana place first and third, respectively. The following day, Tom goes to the hospital for knee surgery, and the girls go surfing with Alana's father Holt and brother Byron. As Bethany dangles her left arm in the water, a tiger shark is swimming just under her surfboard and notices her arm floating in the water. It unexpectedly attacks, ripping off her arm below the shoulder. Holt, Alana, and Byron get her out of the water where Holt makes a tourniquet out of his swimshirt to put on her while Byron calls 911 as Cheri is also informed. An ambulance meets them on the way to the hospital. Just before starting Tom's knee surgery, Dr. David Rovinsky is called to the emergency room to treat Bethany. Besides losing her left arm, she also lost 60% of her blood and Dr. Rovinsky calls her survival a miracle.
The onslaught of paparazzi also proves to be a great strain on her family and their privacy. The Hamiltons are grateful to Holt for his quick and active thinking and decisive action that saved her life. Her injury prevents her participating in the Rip Curl photo shoots, but she wishes Alana well.
Bethany perseveres and after a recuperation period, gets back in the water, and learns to surf with one arm. Inside Edition offers to provide a prosthetic one that is cosmetically perfect and has bendable joints, in exchange for an interview. She angrily rejects it when she learns it will not help her surf as it is not weight bearing, as a result of the size of her arm stump.
Bethany eventually re-enters the competition, telling rival Malina not to go easy on her, and rejects a five-minute head start offered by the judges. She does not perform well because she cannot stay on the board long enough to go out and catch a competitive wave so Malina wins. Disappointed at this loss, she decides to give up competitive surfing and her friendship with Alana is strained following an argument.
Bethany decides to surprise Sarah by joining the youth group on another mission trip to help the people of Phuket, Thailand who were devastated by the 2004 Indian Ocean tsunami. Despite her recent tragedy, she joins her youth group to help the Thai children get over their fear of the ocean. They are understandably afraid of the water, including a little boy. She decides to go into it with a surfboard, hoping this will coax him into it. It works, and the realization that she can use her gift to inspire people motivates her to take up surfing again.
Tom, who believes that Bethany possesses a great surfer's instinct for sensing when the best waves will form, rigs a handle on her surfboard which she can use to prevent falling off while paddling out to the waves, which is not prohibited by the competition's rules. Bethany trains for the competition while rekindling her friendship with Alana. She enters the national championship. During the competition, she performs respectably, though she is still chasing third place. Suddenly, with only minutes left on the clock, the waves die down and all the surfers can only loiter, waiting for the waves to start back up. Tom's belief in his daughter's instinct is proven when she is the only one to sense a big wave forming, and she alone paddles out. When it forms, the others cannot get out in time and she catches it just as the horn sounds. If it is in time, she will win, but the judges rule that the time has expired. Malina is the winner, but she has finally gotten over her differences with Bethany, inviting her up on the platform to share first place.
Subsequently, Bethany lets the reporters interview her. One asks her what she would do if given the chance to undo the loss of her arm. She says that she would still lose it because she can embrace more people now than she ever could with both.

Question: Who did Sarah decide to surprise?
Answer: Sarah