In an experiment done by Griffith it was found that when virulent capsulated smooth 'S' bacteria were injected into healthy mice, the mice dies of pneunomia. When mice were injected with non virulent 'R' forms of same bacteria, they survived and did not die to pneumonia. in another case when S-forms were killed by heating at above `60^(@)C` and injected, rats did not get pneumonia, but when killed, s-forms and R-forms of bacteria were mixed and injected, the rats suffered from pneumonia and died. which one of the following conclusions can be drawn from the above experiment?

Options

A. Heat killed virulent and heat killed avirulent at times can cause disease
B. Avirulent bacteria alone can cause disease
C. Whole body of virulent bacteria is nearest to cause disease
D. Heat resistant component of virulent bacterial cells in combination with avirulent strain can produce the disease

Answer

D