This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
True of the following is/are- 
Select and explain. 
A. IgA crosses placenta, B. Half life of IgG is 23 days, C. IgD is heat stable, D. IgE has highest carbohydrate content
B: Half life of IgG is 23 days
Answer: B: Half life of IgG is 23 days 
Explanation: Half life of IgG is approximately 23days Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pf:96