The argument is about ideas for improved efficiency. It's not clear to whom those ideas are directed toward. Even if we believe those ideas are directed toward employees, the author's main conclusion relates to those same ideas. So the distinction between ideas directed toward employees and ideas directed toward non-employees isn't part of the author's reasoning.

This helps establish that allowing employees to believe they participated in idea generation will lead to getting those ideas implemented more quickly and effectively.

Wrong trigger. What's important is not that the employees participate in a dialogue, but that the dialogue emphasizes the employees’ contribution to ideas. (B) focuses on this element, whereas (C) does not. With (C), we have no reason to think that an employer should try to emphasize the contributions of the employee. (C) gives employers a reason to have a dialogue with employees, but it doesn't give them a reason to have the kind of dialogue specified in the author's conclusion.

Leads to the wrong conclusion. This will lead to the conclusion that allowing employees to participate leads to better ideas, but the argument doesn’t draw that conclusion - it only says the ideas will be implemented more easily.

We already know employees resent suggestions that come from employers, because the employees didn't generate those ideas. The author wants to show that we can get employees to implement these ideas more effectively and quickly if employers emphasize the employees' contributions to those ideas. (E) establishes that employers are more likely to be resented if they try to implement their own ideas rather than the employees'. But the argument is about the employers' ideas and getting those ideas implemented. The author never argues that we should implement different ideas; he argues that we should present the employers' ideas in a way that emphasizes how the employees contributed to them.