"Wow, what a great surprise!" shouted Ernesto.
Here's why:
* Exclamation Mark: The sentence expresses strong emotion (surprise), so it should end with an exclamation mark (!).
* Comma: The comma separates the introductory phrase ("Wow, what a great surprise") from the main part of the sentence ("shouted Ernesto"). This improves readability and clarifies the sentence structure.
* Capital Letter: The word "shouted" starts the main part of the sentence, so it should be capitalized.