6. A universal donor is a person with which of the following blood types? (A) O negative (B) A positive (C) AB positive (D) B negative

## Step 1<br />The problem is asking us to identify the blood type of a universal donor. A universal donor is a person whose blood can be donated to any other person, regardless of their blood type. This is possible because the blood of a universal donor does not contain any antigens that could trigger an immune response in the recipient's body.<br />## Step 2<br />The blood type O negative is considered a universal donor because it does not contain any antigens. This means that it can be safely given to any person, regardless of their blood type.