Which sentence is punctuated correctly?

According to a recent study, the three least popular pizza toppings are: anchovies, eggplant, and pineapple.
According to a recent study: the three least popular pizza toppings are anchovies, eggplant, and pineapple.
Anchovies, eggplant, and pineapple are: the three least popular pizza toppings in the United States.
The three least popular pizza toppings have been revealed: anchovies, eggplant, and pineapple made the bottom of the list.