This setting creates an enchanted mood. For future questions you could figure this out by narrowing down the options, does it make you feel scared or anxious? (Hopefully not) Does it make you feel excited?
The description of white moths that are like stars and the silver trout give this a very magical setting. It's also as if the atmosphere is ephemeral with it's white and silver colors. This creates an enchanted mood. There is not thing in the passage to suggest fear or nervousness which eliminates scared and anxious as possibilities. Also, excited is not correct because there is not an abundance of energy in the passage to suggest excitement.
