A、At low latitudes. B、At mid-latitudes. C、At high latitudes. D、At any latitude. C文章先提出at low latitudes，气候变化不是很大，At mid-latitudes

A country’s latitude, or distance from the equator, has an important effect on its climate. In places located at low latitudes, or near the equator, like Ecuador and northern Brazil, the amount of sunshine changes the least during the year. At mid-latitudes, in places like Japan or Argentina, there is more sunshine in the summer than in the winter. (29) The greatest change occurs at the highest latitudes, in places like northern Canada or Alaska. In these places, the nights are very long for half the year and the days are very long during the other half. At the North or South Pole, sunlight lasts the longest during the summer. But light and heat are the most intense at the equator.
    Latitude and distance from the sea also affect climate. The thin air in high mountain areas absorbs less of the sun’s heat than the thicker air at sea level.
    The daily change in temperature also increases with distance from the sea.
    (30) Snow and rain are very important to climate. Snow reflects as much as eighty or ninety percent of the heat from the sun, and makes the weather even colder. But a large forest area can reflect as little as five percent of the sun’s heat. This makes the weather warmer.
     Of course, the general effects of climate do not explain everything about the weather. For example, (31) both the driest place in the world and the place with the most rainy days are located in Chile. Calama, in the Atacama Desert. has had no rain for over 400 years. But during the year 1916, it rained in Bahia, Felix, Chile for 348 days.