The piece of evidence that would best 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 relies on the idea that individuals are more likely to exhibit altruistic behavior towards their relatives (kin) because it can help ensure the survival and reproductive success of shared genes. In this case, the penguin is protecting its own offspring, which directly relates to the concept of kin selection. The other options involve altruistic behaviors but do not necessarily relate to kin or offspring.