In an Immunodiffusion Test to Diagnose Histoplasmosis, a Patient's Serum

Multiple Choice

In an immunodiffusion test to diagnose histoplasmosis, a patient's serum is placed in a well in an agar plate. In a positive test, a line forms as the serum diffuses from the well and meets material diffusing from a second well. What type of test is this?

A) an ELISA test
B) an agglutination reaction
C) a complement- fixation test
D) a direct test
E) a precipitation reaction