Use the Following Information to Answer the Question(s) Below

Use the following information to answer the question(s) below.
An otherwise healthy student in your class is infected with EBV, the virus that causes infectious mononucleosis. The same student had already been infected when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though infected, she does not get sick.
-Her immune system's recognition of the second infection involves memory ________.

A) helper T cells
B) natural killer cells
C) plasma cells
D) cytotoxic T cells