Answer:
use of cheap labor
Explanation:
Sustainable development simply means that humans must be able to fend for their respective needs without destroying the chance of future generations of meeting their own needs
Therefore, the use of cheap labor does not align with the idea of sustainable development because exploits the workers without paying them adequately.
The correct answer for the question that is being presented above is this one: "B. building of the transcontinental railroad --> disappearance of the frontier." The pair of events that did the first event most directly influence the second is the building of the transcontinental railroad --> disappearance of the frontier.
