Which of the following statements is correct?
A. The mammary glands are a mucosal tissue only after pregnancy
B. All of these statements are correct
C. The combined area of a person's skin is vastly greater than that of the mucosal surfaces
D. None of these statements are correct
E. A similar proportion of all the antibodies made by the body is secreted at mucosal surfaces as the monomeric form of IgG