Answer:
I would say Napping as the answer
Explanation:
-Anxious isn't a good choice, because according to the passage there is a part that says "The "anxious" kitten snuggled to the napping golden retriever." which means that the kitten is nervous or scared.
-Startle can't be the answer, reason is not the answer, because that word describes a sudden shock or panic kind of feeling. In the first sentence to the comma mark, it says "Startled by the thunderstorm." So, it describes that the sound of Thuderstorm is pretty much of a shock sound.
-Frigid wouldn't be the best answer either, because the word describes something that is very cold in temperature. In the last of that passage says "The two snoozed by the fireplace on that Frigid winter night." So, it was meant that the two kittens snoozed by the fireplace on that very cold winter.
The word Napping would be a good choice, because the word napping is mostly a calm word say and it describes sleeping for a small amount of time. So, according to passage after the comma mark, it says "The anxious kitten snuggled up to the napping golden retriever." So, its describes that the kittens snuggled up fireplace and sleep for long time.
