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Writing & Language

One of the primary shortcomings of the Homestead Act of 1862, a program through which the federal government offered free plots of land to US citizens willing to establish farms in the American West, was that the plots were too small to sustain a farm. Land in the semiarid Great Plains region received twenty or fewer inches of rain per year, so plots there were best left half unplanted each growing season to conserve water. With farms consisting of a mere 160 acres, however, this practice would not have produced sufficient harvests. Moreover, raising cattle was impossible because the tiny homesteads would quickly become overgrazed. According to geologist and explorer, John Wesley Powell, sustainable homesteads on the Great Plains actually needed to be a staggering 2,560 acres.

A.NO CHANGE
B.explorer John Wesley Powell,
C.explorer, John Wesley Powell
D.explorer—John Wesley Powell—

答案和解析

答案：B

解析：

Choice B is the best answer because it doesn't unnecessarily set off the restrictive element ("John Wesley Powell") but does set off the long introductory phrase ("According to geologist and explorer John Wesley Powell") with a comma after "Powell."