Based on the question "Why should people recycle?" the two best sources to draw from are:
A documentary describing how recycling programs have positively impacted the environment: This source would provide evidence and examples of how recycling has made a positive impact on the environment. It can help the student build an argument for why recycling is important.
A government website that lists steps citizens can take to reuse products and reduce waste: This source would provide practical steps and tips that individuals can take to recycle and reduce waste in their daily lives. It can help the student build an argument for why recycling is something that individuals can easily do and can make a difference.
The other two sources listed may also have relevant information, but they are more focused on the costs of recycling programs and the process of recycling aluminum, which may not directly address the question of why people should recycle.