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
A child present with recurrent episodes of sinopulmonary infection by bacteria with polysachride rich capsule. Deficiency of which of the following immunoglobulin subclasses should be specifically investigated - 
Select and explain. 
A. IgA, B. IgG1, C. IgG2, D. IgA + IgG2
D: IgA + IgG2
Answer: D: IgA + IgG2 
Explanation: The patients with IgA deficiency have a tendency to develop recurrent sinopulmonary infections, gastrointestinal infections and disorders, allergies, autoimmune conditions, and malignancies. The IgG2 subclass contains antibodies against the polysaccharide coating of ceain disease-producing bacteria that can cause ear and sinus infections, pneumonia, blood infections and meningitis. Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pg.no. : 172,173