This doesn’t shed light on the cause of the lack of government funding. We already know that major alternative-energy intiatives have had government funding curtailed. The issue is whether this is due to large corporations’ actions.

But, is the decision to cut funding to these projects a result of corporations’ actions, or something else? (B) doesn’t help to eliminate other explanations or to affirm the author’s explanation.

This eliminates an alternate explanation that the government was simply cutting funding across the board. (C) establishes a closer connection between having funding cut and corporations’ discouragement.

The author never suggested that the government does whatever corporations want. Some projects encouraged by corporations may have had funding cut. That doesn’t impact whether other projects had funding cut because corporations discouraged those projects.

We already know large corporations have discouraged alternative-energy projects. The issue is whether the government’s decision to cut funding to those projects results from the corporations’ actions. (E) doesn’t help affirm that explanation or eliminate other explanations.