Alison DiLaurentis is A
I think I know why Bethany Young was murdered
Like Mona said on the Fatal Finale "Taking This One To The Grave" Alison was connected to Bethany and Ali knew Bethany,Alison was jealous of Bethany and in the Book "Pretty Little Liars" by Sara Shepard Alison killed her twin Courtney because she was jealous,so in the serie "Pretty Little Liars" by I Marlene King they made some changes.In the book Alison killed Courtney and in the serie Alison is supposed to kill Bethany and Courtney was in mental hospital and in the serie Bethany was in mental hospital.Alison didn't had twin so in the serie she killes Bethany.And when Ali told the girls the history how she disappeared Jessica DiLaurentis was arguing on the phone with someone maybe Bethany escaped and Jessica was worried that's why she said to Ali don't go out tonight 'cause if Ali found Bethany she would kill Bethany 'cause Jessica cared about Bethany and she had something with Bethany's father so maybe in the serie I think Ali lied to the girls maybe Ali wasn't standing there in front of her house Bethany was standing there and Ali hated Bethany 'cause Bethany was more popular and Ali was jealous and she wanted people to care only about her so Ali was behind Bethany and she hit Bethany with a rock that's why she didn't tell no one about it.You know when Ali told the girls a story of two twins fighting over dolls and then one of them killed the other twin this means that Ali didn't had a twin but she killed her half-sister Bethany 'cause they were fighting over other stuff.This is my theory but I'm sure that Alison is A and she killed Mona too ok well I'm not sure that she killed Mona but she had something to do with it.