Your friend wants to add something to her argumentative essay that shows that she favors teens owning smartphones. Which of the following is the most respectful, relevant, and credible statement that could add to her argument?

a Dr. Meryl Ain says, "smartphones can be powerful learning tools, instantly connecting users to information."
b Only one in four teens has experienced bullying "through a mobile device or the Internet."
c Students who use mobile devices to study spend 40 more minutes studying per week.
d The Cyber Bullying Research Center reports that more than 80 percent of teens use a cell phone regularly.

a Dr. Meryl Ain says, "smartphones can be powerful learning tools, instantly connecting users to information."