Final answer:
The true statement about ABO phenotype A2 is that it is associated with increased clotting risk. It is less common than A1 subtype and has a lower expression of A antigens. The A2 phenotype is not limited to individuals of Asian descent and can occur in diverse ethnic groups.
Step-by-step explanation:
The correct statement regarding the ABO phenotype A2 is that it is associated with increased clotting risk. Phenotype A2 is one of the subtypes of blood type A and is less common than the A1 subtype. It is characterized by a lower expression of A antigens on red blood cells. The presence of anti-A or anti-B antibodies varies among individuals with A2 phenotype, just like any other ABO blood type, and does not differentiate A2 from the other subtypes. Therefore, statement a) is incorrect. Statement b) is also incorrect, as A2 is not the most common ABO phenotype; A1 is more prevalent. Statement d) is incorrect because A2 is not limited to individuals of Asian descent and can occur in people of various ethnic backgrounds.