Final answer:
The characters listed are from Agatha Christie's play 'The Mousetrap', not 'The Importance of Being Earnest'. In 'The Mousetrap', Mr. Paravicini arrives unexpectedly at the manor. Therefore, the correct answer is D. Mr. Paravicini.
Step-by-step explanation:
The characters mentioned in the question, Mrs. Boyle, Mr. Wren, Major Metcalf, and Mr. Paravicini, are not part of the play 'The Importance of Being Earnest' by Oscar Wilde, as indicated by the list of characters provided for Act 1, Scene
1. The characters from Wilde's play include Merriman, Butler; Lane, Manservant; Lady Bracknell; Hon. Gwendolen Fairfax; Cecily Cardew; and Miss Prism, Governess. This suggests that the question likely pertains to a different work, potentially Agatha Christie's play 'The Mousetrap', where these names are recognizable.
In Agatha Christie's 'The Mousetrap', Mr. Paravicini is the character who arrives unexpectedly at the manor, amidst a snowstorm and with an outlandish story about his car overturning in a snowdrift. Thus, the correct answer to the question 'Which of our characters/suspects/guests shows up at the manor unexpectedly?' is D. Mr. Paravicini.