Which strategy with a historian most likely use to determine whether a source is valid

Violence has declined in northern ireland because terrorist organizations

Which of the following american companies had a monopoly in the late 1800s? a. deere and company b. sears, roebuck and company c. standard oil company d. general electric company

In 1816, john c. calhoun proposed that: a. that the federal government aid in the construction of roads and canals to improve transportation to and from the west b.the united states should end slavery. c.the united states should increasing the size of the navy and invade central america. d. the united states should annex hawaii