Why are very young children more susceptible to pathogens with T-independent antigens?

• A. Their immune systems do produce antibodies but respond poorly to certain antigens.
• B. They have fewer memory B cells compared to older children and adults.
• C. Their B cells can proliferate, but the response is generally less effective.
• D. They do not have the ability to activate B cells with T-independent antigens.

Answer: (D)