Which of the following events could cause the movement shown in the graph? an increase in population
an increase in the price of a complement
b. a decrease in the price of a substitute d a decrease in income
c.
a

c.an increase in the price of a complement

Explanation:

if there was an increase in substitute, there would have been two graphs indicating which one has increased and which one has decreased ...

if there is an increase for complement such for an example a car,then the demand for petrol (gas) will increase also,complement goods influence each other directly ...if one decrease then the other also decreases...such as the example i gave on early (cars and petrol)

on the whole, dickens has shown the french revolution and its this site might you. good at his job, and the subject matter he chose, 

it would be a. that is the only one i could think of