Why Are Signs and Symptoms Not Quickly Resolved in a Person

Why are signs and symptoms not quickly resolved in a person with tetanus when they are given antibiotics? 

A) Clostridium tetani is an acid-fast organism; it thus has a waxy cell wall that prevents antibiotics from entering the cell.
B) Antibiotics will prevent the production of additional tetanospasmin but will not repair nerves already damaged by the toxin.
C) The antibiotics are given prophylactically, to prevent secondary infections. Nerves damaged by tetanospasmin need time to repair.
D) Clostridium tetani is resistant to most antibiotics; treatment thus involves several weeks of combined antibiotic therapy.
E) Clostridium tetani is an acid-fast organism; it thus has a slow generation time, so it takes several weeks for an antibiotic to be effective in killing the cells.