Which principle of traditional democratic theory is violated when the wealthy have disproportionate influence over government​ decisions?

Principle of Citizen Control of the Agenda is the correct answer.

According to the well-known Political Science professor Robert Dahl, there are 5 principles in his traditional democratic theory. Citizen control of the agenda is one of the basic principles included in the theory. This principle suggests that together citizens should have the right to control of the government's policy agenda. Thus, when the wealthy have a disproportionate influence on government's decisions, the principle of citizen control of the agenda is being violated.