Why are a variety of different sources, both primary and secondary, essential in our understanding of an event or historical time period

Which of following most accurately describes china today?

The 15th amendment to the u. s. constitution, ratified in 1870, deals with what issue? a. prohibition of alcohol b. voting c. declaring war d. free speech

What explains the increase in life expectancy in botswana? a. the increased availability of jobs and an improved economy b. access to antiretroviral drugs, hiv/aids education, and widespread hiv/aids testing c. a series of military takeovers that stabilized the political system and led to education reform and increased literacy rates d. a recent military coup that led to an improved healthcare system select the best answer from the choices provided.