A.I. Explanation:

Option 1: "In modern society we must make more time for our neighbors."

Explanation: This option suggests a focus on personal relationships rather than the main idea of the text, which emphasizes the importance of a standardized measurement of time for societal function. The text does not discuss making time for neighbors, making this option irrelevant.

Option 2: "The traditions of society are timeless."

Explanation: While the text mentions traditions, it specifically focuses on the tradition of timekeeping rather than the general concept of timeless traditions. This option is too broad and does not accurately reflect the main idea presented in the passage.

Option 3: "An accepted way of measuring time is essential for the smooth functioning of society."

Explanation: This option accurately captures the main idea of the passage, which discusses how a common understanding of time is crucial for societal order. The text states that without a single yardstick of time, social life would be chaotic, directly supporting this option.

Option 4: "Friendly relations between neighbors"

Explanation: This option shifts the focus to interpersonal relationships rather than the central theme of timekeeping. The text does not address friendly relations as a main point, making this option incorrect.

Option 5: "People agreement on the measurement of time"

Explanation: This option correctly identifies 'this tradition' as referring to the public acceptance of a single measurement of time. The text emphasizes that this agreement is vital for the functioning of society, aligning perfectly with the main idea.