The correct answer is D.
The graph represents the % of male and female voters in five different age groups. The figures show that, the older the age represented by a group, the larger the percentage of voters it contains, both in the case of men and of women. Therefore there is a clear direct relationship between age and percentage of voters and a greater share of older people vote, if compared to younger age groups. D is the only alternatively that fulfills all the abovementioned features of the graph.