The best piece of evidence to support the argument for Kin selection as a mechanism for the evolution of altruistic behavior would be a study showing that individuals are more likely to help their close relatives than unrelated individuals. This could be demonstrated by examining the behavior of organisms towards their kin in various situations that require cooperation or sacrifice. Additionally, evidence of genetic relatedness influencing the degree of altruistic behavior would further strengthen the argument for Kin selection as a driver of altruism evolution.
