The sentence that helps readers determine the story's setting is:
"The morning mist was completely gone. The sun was strong and bright, intensifying the color of a row of potted marigolds on the front porch of one of the houses."
This sentence provides details about the weather and the environment, giving readers a sense of the time of year (likely summer) and the physical surroundings (such as the sun and marigolds), which contribute to the overall setting of the story.