Which of the Following Statements About the Weil-Felix Test for Typhus

Which of the following statements about the Weil-Felix test for typhus is false?

A) It relies on the fact that antibodies generated against Rickettsia do not react with Proteus OX19.
B) It relies on cross-reactivity between the pathogen and the soil bacterium.
C) When blood serum is drawn from a person to be tested, the serum is mixed with a solution containing Proteus OX19.
D) Humans are not normally infected with Proteus OX19.
E) If the individual being tested is positive, clumping will be seen on the test slide.