In a crowded mall parking lot, dozens of people hear a female voice yell, "he's killing me! " yet no one calls the police. what is the reason for the lack of action, according to darley and latane'?

I believe the correct answer is diffusion of responsibility.
According to Darley and Latane, what might happen in such a case is diffusion of responsibility. This means that these bystanders will believe that someone else will call for help, so that they don't have to do it. However, if everyone thinks this way, ultimately no one will help the woman in danger.

C. equitable; undue influence