Final answer:
The statement is true because naive B cells need two signals to differentiate and produce antibodies: antigen recognition and cytokine signals from helper T cells.
Step-by-step explanation:
The statement that recognition of antigen (Ag) alone is not sufficient to drive naive B cells to differentiate and produce antibodies (Ab) is true. Naive B cells require two signals for activation. First, their surface immunoglobulin must recognize and bind to the native antigen.
Second, the B cell needs additional signals typically provided by helper T cells (Th2 cells) in the form of cytokines. This is due to the presentation of processed antigen fragments on the B cell's surface along with class II MHC molecules, which the T cell recognizes, leading to its activation and the secretion of cytokines. These cytokines then activate the B cell completely, allowing it to differentiate into a plasma cell that secretes specific antibodies.