There are actually 4 blood forms: A, B, AB, or O. Also, blood is possibly Rh-favourable or Rh-destructive. So if you have type A blood, It is really either A favourable or simply a detrimental. Which sort you're is very important if you need a blood transfusion. Plus your https://www.youtube.com/watch?v=buIHtQY7fCU