Question

what is the main reason politicians spend millions of dollars on advertising during elections? to reinforce their messages to dissuade people from voting for their opponents to influence undecided voters to generate donations

Explanation:

Undecided voters can sway election results. Advertising aims to win their support by presenting the politician's platform and qualities. While other options may be secondary effects, influencing undecided voters is the primary goal.

Answer:

to influence undecided voters