Which of the following statements regarding blood are true and which are false?

a. The normal pH of blood varies from 7.5 to 8.5. The RBC type O is the most common type and also the universal donor.
c. RBC type AB means that both alpha and beta chains are present in the hemoglobin.
c. Plasma distributes heat from warm organs such as skeletal muscles to cooler body areas.
d. The HLA types contribute to the immune system's ability to recognize self and distinguish self from foreign.