This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Inheritance pattern of ABO blood group system is 
Select and explain. 
A. Pseudodominance, B. Autosomal dominant, C. Autosomal recessive, D. Codominance
D: Codominance
Answer: D: Codominance 
Explanation: harshmohan textbook of pathology 7th edition ABO blood grouping shows codominance as both alleles of a gene pair are expressed in heterozygous state