Which of the following syllogisms is valid?
All human beings have three legs; Tom is a human being; therefore, Tom has three legs.
All Denver Broncos are smart; all Denver Broncos are strong; therefore, all football players are smart and strong.
Joan likes Frank Sinatra; Jill likes Christina Aguilera; therefore, Jill dislikes Frank Sinatra.
All Finns have beards; Mikko is a Finn; therefore, all Finns are named Mikko.