which of the following topics is most appropriate for a 10-minute informational speech?

a -you speech to guests who have come to a party

why breakfast is the most important meal of the day

how to train a dog to stay

the u. s. government

"why breakfast is the most important meal of the day"

I say this becasue talking about the U.S Government could take more than 10 minutes.
Also when you're "training" someone its a long process, so talking to someone about training your dog could take even longer.
Also when you're typically "thanking someone for coming to your party" it's a long list. (unless you had a party with like, 3 people. but whats a party with only 3 people?? o.o )so that crosses off "a thank-you speech to guests who have come to a party"

Hope this helps.