Which statement is TRUE about Streptococcus pneumoniae and the lung infection it causes?

Which statement is TRUE about Streptococcus pneumoniae and the lung infection it causes?
A) Streptococcus pneumoniae can spread from the focus of infection as a bacteremia.
B) Penicillin and erythromycin are the last chance drugs for treatment of streptococcal pneumonia.
C) Infection with any strain of encapsulated virulent Streptococcus pneumoniae provides long-lasting immunity to all encapsulated virulent strains.
D) Streptococcal pneumonia is not as serious as most people think; if left untreated, it usually runs its course in about a week to ten days.