Final answer:
Rhnull individuals lack the Rh antigen on their red blood cells.
Step-by-step explanation:
Rhnull individuals lack the Rh antigen on their red blood cells. The Rh antigen is a protein and is designated as Rh positive (Rh+) when present and Rh negative (Rh-) when absent.
Therefore, the correct answer is 3) Spherocytes.