The best piece of evidence to support the argument for kin selection as a mechanism for the evolution of altruistic behavior is:
a penguin protects its chick from seagulls.
Kin selection suggests that individuals are more likely to exhibit altruistic behavior towards their relatives to enhance the survival of their shared genetic material. The behavior of a penguin protecting its chick directly illustrates this concept, as the action benefits its offspring, which share a significant portion of its genes.