Lydia was bitten by a fire ant. The bite hurt and itched, but wasn't very bad and cleared up quickly. A few months later, she was bitten by a second fire ant. This time, the bite rapidly swelled, became very red and hot, and she developed itchy patches all over her body. Why were her symptoms so much worse the second time she was bit? A Lydia was not allergic to the first type of fire ant but she must have been bitten by a different type of fire ant that she was allergic to.

B Lydia was always allergic but the first time the ant was very small.

C When Lydia was bitten the first time, her body created antibodies and memory cells against the venom and the second exposure elicited a stronger reaction.

D When Lydia was bitten the first time she had not yet developed the antibodies in her Thymus.