One of these things is not like the others.
Please go to the Question #2 post if you haven't had a chance work on this one yet, since the text below contains the solution.
Unlike the previous question, this time none of the words should be unfamiliar. The solution here relates to the sources of each of the substances. Three of the four items are animal products, while the fourth is not.
Honey, of course, is produced by bees. Silk is made by silkworms. Gelatin is made from the collagen in the skin and bones of various animals. But cotton is not an animal product, so it does not belong on the list. It is not like the others.