Final answer:
The sentence that contains an idiom is: 'Phil annoyed everyone when he rode in here on his high horse and started criticizing all of our decorations and party supplies.'
Step-by-step explanation:
The sentence that contains an idiom is:
Phil annoyed everyone when he rode in here on his high horse and started criticizing all of our decorations and party supplies.
In this sentence, the idiom 'on his high horse' means that Phil was behaving arrogantly or pretentiously.
Learn more about Idioms in English sentences