In 1801, a Blackfoot chief named Ac Ko Mok Ki drew a ﬁnely detailed map of the Upper Missouri region. This work
demonstrates a vast amount of topographic knowledge, as the map features speciﬁc names of mountains and rivers, as well
as the ﬁrst-known sketch of the drainage network of the Missouri River. The map is especially notable because Ac Ko Mok Ki
also included details about the numerous tribes that lived in the area.
It emphasizes Ac Ko Mok Ki’s desire to represent other tribes on the map.
It explains how Ac Ko Mok Ki developed an interest in mapmaking.
It identiﬁes some reasons why the map is impressive.
It details how the map was used for hunting and trading purposes.
Choice C is the best answer because it best describes how the underlined sentence functions in the text as a whole. The text
presents information about a map drawn by Blackfoot chief Ac Ko Mok Ki in 1801. The underlined sentence states that the
map "demonstrates a vast amount of topographic knowledge" and mentions that it features the "speciﬁc names of
mountains and rivers" and includes the ﬁrst-known sketch of the Missouri River’s drainage network. These are all
characteristics that indicate that the map was executed with remarkable skill. Thus, the underlined sentence identiﬁes some
reasons why the map is impressive.
Choice A is incorrect. Though the sentence after the underlined sentence in the text mentions that Ac Ko Mok Ki included
information about other tribes on his map, the underlined sentence itself does not address this topic. Choice B is incorrect
because nothing in the underlined sentence indicates how Ac Ko Mok Ki became interested in mapmaking, only that his
mapmaking skills are impressive. Choice D is incorrect because though the underlined sentence describes several features
of the map, it does not speciﬁcally describe how the map was used.