You Are a Doctor Who Examines a Swollen and Warm

You are a doctor who examines a swollen and warm puncture wound on the hand of a patient, which was caused by a rusty nail. You vaccinate her for tetanus. In her body's response to the vaccine, how does one of her B cells produce antibodies against C. tetani?

A) Each antigen is coded for by a unique gene in the human genome; the correct gene is expressed to produce the antigens against C. tetani.
B) Rearrangement of different gene segments in B cells after exposure to C. tetani creates a unique gene. The cell then produces lots of that specific antibody.
C) Post-translational modification of a generic antibody protein changes it from a generic form to a specific form against C. tetani.
D) Rearrangement of different gene segments in maturing B cells creates a unique gene. Upon exposure to C. tetani, the cell is stimulated to produce lots of that specific antibody.