(EEAR 2016/2017 ) - QUESTÃO

 The sentence "lf young people don't control the hours they spend on-line, they won't stay out of trouble." can be correctly replaced by: 

a) Unless young people control the hours they spend on-line, they will stay out of trouble.
b) Unless young people control the hours they spend on-line, they won't stay out of trouble. 
 c) lf young people controls the hours they spend on line, they will unless stay out of trouble. 
d) Unless young people don't control the hours they spend on line, they won't stay out of trouble.

IsUnless significa if not.