1. George Stephenson A. Steam locomotive 2. Robert Fulton B. Telegraph line 3. Cyrus McCormick C. Steamboat 4. John Deere D. Sewing machine 5. Samuel F. B. Morse E. Telegraph and Morse code 6. Ezra Cornell F. Cotton gin 7. Eli Whitney G. Riding plow 8. Elias Howe H. Horse-drawn reaper

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation:

a is your answer

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health care plans in the united states having high costs because they are focusing on providing quality programs for different groups of individuals. the quality of the service is based on money flow received from the members. without this investment, couldn't be possible a constant scientific searching to prevent death and illness caused because of low levels of health investigation. currently, the complaints are not about the highest cost, but about the coverage and benefits to access the necessary health services required by the members.  

besides, if a global health system is established the quality levels will fall down because of the standardized of the health. the access to care will increase but the quality will be low because it depends on the money invested.