I believe the choice that best captures the key hindrance to the sustainability movement based on those options is:
c. banks and other financial institutions continue to focus solely on short-term gains
While the costs of renewable energy sources, corporate willingness to pay higher prices, and government/regulatory commitments to sustainability are also relevant factors, the primacy of short-term financial gains suggests an underemphasis on the long-term, large-scale investments required to truly accelerate the transition to more sustainable energy and economic systems. Reducing the time horizon and risk aversion of financial institutions could help unlock more resources and funding for renewable energy projects, green technologies, and other sustainability initiatives that may have slower payback periods but critical long-term benefits.
So in summary, I see choice c as capturing the most significant systemic challenge posed to rapid progress on sustainability according to the options provided. Let me know if you have any other questions!