Final answer:
The carbon tax proposal failed in Washington state due to opposition from industry and business groups, lack of support from voters, and political challenges.
Step-by-step explanation:
The carbon tax proposal failed in Washington state for several reasons. One of the main reasons is the opposition from industry and business groups who argued that the tax would hurt their competitiveness and lead to job losses. Another reason is the lack of support from voters who were concerned about the potential increase in energy costs.
Additionally, the proposal faced political challenges as some lawmakers were not convinced of the need for a carbon tax or were opposed to it on ideological grounds. These factors combined to prevent the proposal from gaining enough support to pass.