There are actually four blood types: A, B, AB, or O. Also, blood is either Rh-constructive or Rh-negative. So When you have kind A blood, it's either A beneficial or maybe a detrimental. Which sort you're is essential if you want a blood transfusion. Along with your Rh element https://allkindsofsocial.com/story5263235/about-blood-castle-mu-online