At three years old, Louise Braille had a condition most children never have to worry about. He was blind. While growing up, he felt that he did not want to be a burden on his family. He wanted to be an active member of society and not let this complication hold him back. Since he was unable to see words to read, he needed a solution that would enable him to read without sight. He solved his problem by creating a series of bumps taken from military code that represented words. This new type of reading was called Braille. People without sight still use Braille as their main source of reading. Thanks to 15-year-old Louise Braille, people who are blind can live normal lives.

Which key words does the author use to organize this text in a problem and solution text structure?

Cause, effect
Complication, solved
Since, now
While, still