阅读下面四篇短文，从每题所给的A、B、C、D四个选项中选出最佳选项。
B
Recently，there was a report about a special app called "notOK"．A 13-year-old girl Hannah Lucas and her brother Charlie put their heads together to create this app last year．
Hannah has been suffering from an illness that causes her to pass out since she was little．This is very dangerous if there is no one around．She was also being bullied(欺凌)by some students at school．So she searched for an app that would allow her to press a button so that a friend or a family member would know immediately that she needed help．After realizing there was no such thing，Hannah and her brother decided to do something about it．After some research，Hannah made some early drawings of what the app might look like．Then，after taking a programming class，Charlie began to think about the best way for the app to work．
They wanted something that would send a text message to up to five contacts that reads："Hey，I'm not OK．Please call me，text me，or come and find me"，along with a link to the user's current GPS location．
They started looking for someone to help them make the app．And when Hannah shared her dream with people in a summer business class which she attended two years ago，they were really excited about the app．They thought of many different marketing ideas．By mid—December last year, "notOK" app was finished as a birthday present for Hannah from Charlie．"It was exactly what we wanted，"Charlie said．
In today's age，most people will agree that apps like these are great．Whether you're suffering from illness，or anything emergent(紧急的)，writing a text message or making a phone call to get the help you need can be difficult．
Hannah is happy to know that her app will help more people．"It's like I went through my dark times so I could help people through theirs，"she said．
