Which of the drugs below is known as the "gateway drug" since it can pave the way to "harder" or more illegal drugs?

i need the a b or c but mental disorders include repetitiveness,unable to listen, wanting to kill people, thinking that you are perfect, sexuality toward the wrong age types younger than you like a child bad reputations cutting yourself abuse! these are sad but these are true! the titles for some of these are ptsd and adhd. you need to go to jail or get an expert counselor if you face any of these problems or if you have indeed been involved!

answer; monaxial;