The correct answer is D. Guests looked at me with a mixture of shock and amusement.
Explanation
The author wrote this text with the purpose of entertaining the audience. This is evidenced by the fact that he begins the story with an expectant phrase "Just try not to laugh as I tell you about the time I made my sister a birthday cake!" He then develops the story in which he tells that he is following a recipe to make the birthday cake. However the conclusion of the text is finally revelated when the author says that part of the cake had been raw inside, also this idea is reinforced by this phrase "Guests looked at me with a mixture of shock and amusement". Therefore, the correct answer is D. Guests looked at me with a mixture of shock and amusement.
