Kingsnake and stick insect are the most closely related among the options provided.
This is because both kingsnakes and stick insects are reptiles and insects, respectively, which are part of the animal kingdom. However, goldfish (fish) and dogs (mammals) are also in the animal kingdom, but they belong to different classes.
In a strict sense of evolutionary relationships based on shared ancestry, the kingsnake (a reptile) and the stick insect (an insect) are more closely positioned on the tree of life than goldfish or dogs. However, if we consider close relationships at the class level (reptilia for kingsnake), the correct answer will depend more on the context of the question. Generally, in terms of evolutionary closeness, kingsnakes and stick insects would be grouped closer as they share a more recent common ancestor compared to other pairs in the options.
So, the answer to your question about which species are most closely related is generally more nuanced, often leading us to look at finer classifications within the broader groupings.