What is the plural possessive form of speaker?

Which is an example of finding common ground when addressing a counter argument? a. products with genetically modified organisms (gmos) in them are frankenfoods that are unnatural, dangerous, and foul tasting. b. it’s really not important that some people feel texting while driving isn’t a big deal; it’s a fact that it’s dangerous and should be illegal. c. while both sides agree that processed foods are more convenient, the damage they do to a person’s health should not be ignored. d. testing on animals has produce several lifesaving vaccines and medicines that have saved countless human lives.