(急) 求问一道阅读机经题

Recent studies of ancient Maya water management have found that the urban architecture of
some cities was used to divert rainfall runoff into gravity-fed systems of interconnected
reservoirs. In the central and southern May Lowlands, this kind of water control was necessary
to support large populations throughout the year due to the scarcity of perennial surface water
and the seasonal availability of rainfall. Some scholars argue that the concentration of water
within the urban core of these sites provided a centralized source of political authority for
Maya elites based largely on controlled water access. Such an argument is plausible,
however, it is less useful for understanding the sociopolitical implications of water use and
control in other, water-rich parts of the Maya region.

Consider each of the choices separately and select all that apply.
2. According to the passage, which of the following is true of the water management systems
in the central and southern Maya Lowlands?
A. They were implemented in part because of the prevailing pattern of rainfall.
B. They were an integral part of lowland cities' architecture.
C. They were needed because of insufficient resources such as ponds, rivers and lakes in the
lowlands.

不知道大家做过这篇阅读没。。KMF解析说是ABC，但原因很brief，就说只是因为文章第一句话。去网上搜很少人问，有的人说B不对，KMF旧官网却没给这题的答案，不知为啥。B不对的原因感觉是因为第一句话的some cities, 所以不是很integral。但第一句话并不只是指Lowland cities，反而文章第二句话说对于Lowland cities，这种water system is necessary，似乎又很integral。求问各位大神！！感谢！