Question

Match the following antibodies with their correct description:

Antibody	Description
P. IgE	(i) Cross the placenta
Q. IgG	(ii) Dominant antibody produced in immune responses
R. IgM	(iii) It is found in the mother's milk
S. IgA	(iv) Responsible for autoimmune responses including allergies

• A. P(i), Q(iii), R(ii), S(iv)
• B. P(i), Q(ii), R(iii), S(iv)
• C. P(iv), Q(ii), R(iii), S(i)
• D. P(iv), Q(i), R(ii), S(iii)

Hint:

- IgE is involved in allergic reactions, IgG crosses the placenta to provide immunity to the fetus, IgM is the first response antibody, and IgA is found in mucosal areas like breast milk. 
- These antibodies are key to understanding immune responses and vaccine development.

Answer 1

The Correct Option is D

The following are the descriptions for each antibody: 
- P. IgE: (iv) Responsible for autoimmune responses including allergies. IgE is involved in allergic reactions and immune responses to parasites. 
- Q. IgG: (i) Cross the placenta. IgG is the only antibody class that can cross the placenta, providing passive immunity to the fetus. 
- R. IgM: (ii) Dominant antibody produced in immune responses. IgM is the first antibody produced during an immune response and is crucial in the early immune defense. 
- S. IgA: (iii) It is found in the mother's milk. IgA is the primary antibody found in mucosal surfaces such as breast milk, providing passive immunity to the newborn. 

Thus, the correct matching is P(iv), Q(i), R(ii), S(iii).

Answer 2

This question checks whether each immunoglobulin class is paired with its correct biological role: IgE, IgG, IgM, and IgA. The fastest way to find the right combination is to fix the correct role for each antibody first, then see which lettered option matches all four at once.

1. P(i), Q(iii), R(ii), S(iv): This pairs IgE with crossing the placenta and IgG with being present in breast milk, both wrong. IgE is the antibody behind allergic and parasitic responses, and IgG, not IgA, is the one that crosses the placenta.
2. P(i), Q(ii), R(iii), S(iv): This pairs IgE with crossing the placenta, which is incorrect since IgG performs that role, and it also swaps IgM and IgA's descriptions.
3. P(iv), Q(ii), R(iii), S(i): IgE with allergic responses is correct, but this option pairs IgG with being the dominant antibody produced, which actually describes IgM's role as the first responder, and it pairs IgM with breast milk, which is IgA's role, and IgA with crossing the placenta, which is IgG's role. Every remaining pairing is swapped.
4. P(iv), Q(i), R(ii), S(iii): IgE is tied to allergic and autoimmune type responses, which is correct. IgG is the only antibody class that crosses the placenta to protect the fetus, which is correct. IgM is produced first and in the largest amount during an early immune response, which matches being the dominant early antibody, correct. IgA is the antibody found concentrated in mother's milk and mucosal secretions, correct. All four pairings hold up.

Checking each antibody's real biological role against every listed combination shows that only the fourth option gets all four pairings right at once.

Therefore, the correct answer is P(iv), Q(i), R(ii), S(iii).