On the first day of school, Jack found a little old lady with a warm smile."Hi, handsome. My name is Rose. I'm 87 years old."she said. "Why are you in university at such a YOUNG age?" Jack asked. "I'm here to meet a rich husband, get married, have a couple of kids, and then retired and travel." she answered. Jack knew she's joking but he was surprised what encouraged her to be here at her age. "I always dreamed of having a university education and now I'm getting one!" she told me. We became friends. Every day they would talk after class. Jack always enjoyed listening to this "time machine" as she shared her wisdom  and experience with him. And Rose easily made friends wherever she went. At the end of the term, Rose was invited to make a little speech. She said, "We don't stop playing because we're old. We grow old because we stop playing. Being happy and achieving success may keep you staying young. If you have a dream, hold on. When you lose your dreams, you die." "Anybody can grow older. _ doesn't take any talent  or ability. The idea is to grow up by always finding the chance in change..." What does the word that in Para.7 refers to ?
Growing older. Growing up Staying young Being happy