You are answering a USMLE-style medical question. Question: A medical student decides to join an immunology research center, which specifically works on capsular polysaccharide vaccine development against bacteria, such as Haemophilus influenzae type b (Hib), Neisseria meningitidis, and Streptococcus pneumoniae. As a member of a research team working on the Hib vaccine, he asks his senior colleague why capsular polysaccharides are conjugated to protein carriers like tetanus toxoid during vaccine development. Which of the following is the best response to this question? Options: A) Conjugation with a protein carrier generates IgG2 dominant antibody responses B) Conjugation with a protein carrier generates IgM dominant antibody responses C) Conjugation with a protein carrier improves vaccine stability D) Conjugation with a protein carrier provides effective protection to infants Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.