Why Are Races for Statewide Offices,such as the Assembly and Senate,so

Why are races for statewide offices,such as the Assembly and Senate,so expensive?

A) money is easy to obtain,so politicians spend it
B) the most efficient,but also the most expensive,way to reach large numbers of voters is through paid media (such as television advertisements)
C) campaign managers demand exorbitant fees,which drives up the cost of elections
D) wealthy candidates always participate in enough campaigns so that they drive up the cost of all elections