It had smaller population around 2 million
The answer is: [C]: continentality .
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Pre-Awareness to prepare for the eruption of the volcano
-- The low tides would be lower, and the high tides would be higher.
-- The time from a low tide to a high tide, or from a high tide to a low tide,
would average 6hrs 24min, instead of the present 6hrs 12.2min.
(By the way ... the moon revolves around the Earth in 27.32 days.
That "30 days" that you mentioned is close to the complete cycle
of the moon's phases ... 29.53 days ... which the tides also follow.)
I think the answer is A good luck
