Upon centrifugation of an antibody screen procedure done by the gel system, the red blood cell agglutinates are dispersed throughout the gel column with a few agglutinates at the bottom of the microtubes.

This reaction should be graded as a:

A. 4+
B. 3+
C. 2+
D. 1+
E. Negative

The correct answer is option C. "2+".

Explanation:

A common procedure to test for the presence of antigens is to perform an agglutination reaction by performing an antibody screen. In an agglutination reaction that is graded  2+ the red blood cells start to be broken and medium-sized agglutinates are formed. In this reaction no red blood cells are free, only agglutinates are seen at the bottom of the microtubes. The characteristics of the reaction herein described concur with an agglutination reaction that is graded  2+.

"a.) well–developed vascular system."