A historian researching economic systems in the nineteenth century would find the data in the chart most helpful in

This historian would find graphical data that exposed information about the causes of European imperialism during that period of time more useful.

Explanation:

During the 19th century, European imperialism was one of the most important and influential economic factors, dominating much of the world economy. For this reason, a historian who was researching the economic systems in force at that time, would find great use in a graph that presented information about imperialism, mainly information that focused on the causes of imperialism at the end of this century.

d. migration

i thinl it is the 1st answer