Final answer:
Among the given options, a person daydreaming and not paying attention to their surroundings is most likely to notice a red fire truck drive by, due to a higher availability of attentional capacity.
Step-by-step explanation:
The concept described in the question is known as inattentional blindness, which is a psychological phenomenon where an individual fails to perceive an unexpected stimulus in plain sight. When considering the scenarios provided, option d) A person daydreaming and not paying attention to their surroundings is MOST likely to notice a red fire truck drive by. This person, being less engrossed in any particular activity, has more available attentional capacity.
In contrast, the person focused on their smartphone (option a), engaged in deep conversation (option b), and searching for an item in a cluttered room (option c), are all deeply invested in tasks that require focused attention, making them more susceptible to inattentional blindness.