'Drug antagonism' is described as the mechanism that is based on interactivity among the two drugs in which one hampers the action of the other as they both have an opposite or contradictory impact on the human body. In such a mechanism, one drug inhibits/blocks or affects another's efficacy due to their interaction.
In the given example, the less effective impact of insulin is due to 'drug antagonism' as the interaction of 'anti-rejection' medicines and the 'insulin' led to this effect in which the medicines(drug) have reduced the effectiveness of insulin(another medicine). Therefore, <u>option B</u> is the correct answer.
