A.I. Explanation:

Option 1: "overlooked"

Explanation: The correct answer 'overlooked' fits perfectly in the context of the sentence, as it implies that critical warning signs of Alzheimer's disease should not be missed or disregarded. The text emphasizes the importance of recognizing symptoms early to provide appropriate care, making 'overlooked' a suitable choice that aligns with the overall theme of vigilance and awareness.

Option 2: "ignored"

Explanation: The option 'ignored' suggests a conscious decision to not pay attention to the warning signs. While it may seem similar to 'overlooked,' it carries a more negative connotation that implies willful neglect, which is not the intended meaning in the context of the text. The text encourages awareness rather than suggesting that people would actively ignore the signs.

Option 3: "overdue"

Explanation: The term 'overdue' refers to something that is late or past its expected time. This does not fit the context of the sentence, which is focused on the importance of recognizing symptoms early. Using 'overdue' would imply that the warning signs should have been recognized earlier, which does not align with the proactive approach suggested in the text.

Option 4: "unnoticed"

Explanation: While 'unnoticed' might seem relevant, it lacks the active implication of missing something important that 'overlooked' conveys. 'Unnoticed' suggests that the signs simply went unseen, but the text emphasizes the need for awareness and recognition, making 'overlooked' a more precise fit for the intended message.