Final answer:
Option (b) 'I was casually strolling with Sam when he unexpectedly expressed gratitude for my care' most clearly uses a magical realist tone by presenting the extraordinary event in an ordinary context.
Step-by-step explanation:
The student has asked which rewrite of the underlined portion of a passage most clearly uses a magical realist tone. Magical realism involves incorporating magical elements into a realistic setting in such a way that it feels natural and believable within the narrative's context. Option (b) 'I was casually strolling with Sam when he unexpectedly expressed gratitude for my care' achieves this by presenting the extraordinary event of a dog speaking as if it occurred during an ordinary walk in the park, hence reflecting the seamless blend of the magical with the mundane characteristic of magical realism.