Final answer:
The best supporting detail for Susan's speech on the importance of recycling is that in 2006, there were more than $1.2 billion worth of recyclables thrown away.
Step-by-step explanation:
The best supporting detail based on Susan's purpose of writing a speech about the importance of recycling would be option B:
In 2006, there were more than $1.2 billion worth of recyclables thrown away.
This detail provides concrete evidence of the importance of recycling by highlighting the significant value of recyclables that were wasted. It emphasizes the financial aspect of recycling and showcases the potential economic benefits that could be realized through recycling efforts.