When talking about recycling, people don't seem to consider the recycling of clothing.
The comma should be placed between the first use of recycling and people. The subordinate clause is "when talking about recycling". This is a clause because of the word "when". When makes the reader wonder when what? The main clause is "people don't seem to consider the recycling of clothing."
He tells Jem he has perpetrated a near libel. A libel is a legal term meaning a published false statement that is damaging to a person's reputation. Atticus, is of course joking with Jem, but he asks the children to make the snowman a little less like Mr. Avery
D) all of them correctly connected the independent clause with the dependent clause