Anti-D and anti-C are identified in the serum of a transfused pregnant woman, gravida 2, para 1. The most likely explanation of the presence of anti-C is that this antibody is:

The presence of anti-C in the serum of a transfused pregnant woman can be attributed to the possibility that it is actually anti-G. This is significant because anti-G can react with both the D (Rh) and C antigens on red blood cells. In patients who are Rh negative and have been sensitized, particularly during pregnancy or transfusions, anti-G can form as a result of exposure to Rh-positive red blood cells.

The presence of anti-G mimics anti-C because it shares similar immunologic properties, leading to potential confusion in serological testing. Since the woman in the question has been transfused, it is plausible that she was exposed to antigens that led to the production of anti-G rather than anti-C alone.

Understanding this helps clarify the serological responses in individuals who have been sensitized or transfused, particularly in the context of pregnant women, where heightened vigilance is necessary due to potential complications with Rh incompatibility and the effects on the fetus.