Question

Which sentence sets a formal tone? Hello, and what a hoot it was to make your acquaintance last week. Hey, good to meet you at the party last week. Hey, wasn't that an awesome party last week? Hello! I was very pleased to meet you at the party last week.

Answer 1

The last answer sets the most formal tone; "Hello! I was very pleased to meet you at the party last week." the rest are very casual.