Final answer:
Josie Silver's distinct writer's voice gave her away as the author of a novel published under a pseudonym, as her voice includes unique stylistic elements recognizable by her readers.
Step-by-step explanation:
The literary term that best describes what gave Josie Silver away as the writer of a historical fiction novel published under the pen name Lydia Foreman is her voice.
A writer's voice is the distinctive style and perspective that is inherently part of their writing, and it includes aspects like tone, pacing, syntax, and the way they structure their narratives.
Readers who are familiar with Silver's previous work as a mystery writer were able to recognize that unique voice, thereby attributing the work to her despite the use of a pseudonym.