Answer: A) #1 and #2
You just finished that great yogurt and, after looking for and finding the recycling symbol, placed the container in the recycling bin, assuming it would be recycled. Unfortunately, if that container didn't have a number 1 or 2 inside the recycling symbol, then it may not be recycled. That's because numbers 1 and 2 (PETE and HDPE plastics) are the easiest to recycle. In truth, there are far fewer facilities that recycle numbers 3-7 (in general, the higher the number, the harder it is to recycle). The numbers refer to the kind of plastic the container is made from; this is important because different plastics melt at different temperatures, and have different compatibilities with one another.
Source: Recycle Arizona