【单选题】Which is not true for the development and aging of ABO system?
A.
ABO antigens can be detected on red cells of embryos as early as 5 to 6 weeks of gestation.
B.
Adult levels of ABO expression are generally present by age 2 to 4 years.
C.
Endogenous synthesis of anti-A and anti-B can develop as early as at birth, with nearly all children displaying the appropriate isohemagglutinins in their sera at 3 to 6 months of age.
D.
Titers of anti-A and anti-B continue to increase during early childhood and achieve adult levels within 5 to 10 years.