Correct option is D
Explanation-
The goal is to find which group of mice will generate a secondary anti-hapten response to DNP.
Hapten: Small molecule (like DNP) that is not immunogenic on its own but becomes immunogenic when attached to a carrier protein (like BSA or OVA).
T-cell help is essential for B cells to generate a secondary (memory) antibody response to haptens.
X-ray irradiated mice cannot mount immune responses by themselves — they need adoptive transfer of functional immune cells.
Experiment A: Mice are injected with spleen cells from both DNP-BSA-primed mice (have B cells specific to DNP) and OVA-primed mice (have T cells specific to OVA).
Challenge: DNP-OVA
Result: DNP-specific B cells can bind the DNP hapten. OVA-specific T cells can recognize OVA and provide T-cell help.
Secondary anti-DNP response is possible.
Experiment B: Mice get T-cell depleted spleen cells from DNP-BSA-primed mice (only B cells specific to DNP) and full spleen cells from OVA-primed mice (T cells for OVA)
Challenge: DNP-OVA
Result: B cells recognize DNP and T cells recognize OVA and provide help.
Secondary anti-DNP response occurs.
Experiment C: Mice get full spleen cells from DNP-BSA-primed mice and T-cell depleted spleen cells from OVA-primed mice
Challenge: DNP-OVA
Result: T-cell help is absent (OVA-specific T cells are missing).
No secondary anti-DNP response.
Final Answer: Option D (The mice in experiments A and B) will generate the desired response.
