Final answer:
Mrs. Slade's husband was an architect in Edith Wharton's 'Roman Fever'. This detail is relevant to the novella as it contributes to the social backdrop and characterization within the story. (d) An architect.
Step-by-step explanation:
The profession of Mrs. Slade's husband in Edith Wharton's novella 'Roman Fever' is actually option (d) An architect. The storyline revolves around two middle-aged women, Mrs. Slade and Mrs. Ansley, who reflect on their respective pasts and the lives they have led. The late Mr. Slade's occupation as an architect is pertinent since it adds to the social status and the character development in the novella.