There's an additional distinction that should help you see what separates B and E. The sociologist's first statement gives a reason to avoid generating efficiency ideas from higher up the corporate ladder. The subconclusion and conclusion state:
employer emphasizes employees' positive contributions to ideas -> ideas implemented more quickly and effectively
It's a basic if/then statement, broken into two sentences. E supports the initial premise by providing additional evidence why the rejected approach should not be used. However, we don't need additional support for the premise. We need to strengthen/support the conclusion. B, on the other hand, provides a reason to believe that the if/then conclusion is valid. Conditionally, B looks like this:
employees believe they participated in generating ideas -> employees more likely to carry out those ideas
We now have an additional reason why the approach advocated by the sociologist would be effective in implementing changes. In short, E supports a premise, while B supports the conclusion.