Which sentence from the passage is an example of an opinion disguised as fact?
a. “In 1980, about 23 million people spoke a language other than English at home, but now almost 60 million people do.” (paragraph 2)
b. “Whether traveling abroad for business or pleasure, you are likely to meet people who speak English—at least in the larger cities.” (paragraph 5)
c. “There were 26 million more Spanish speakers in 2010 than there were 30 years before, and other languages are being spoken more and more frequently, such as Vietnamese and Russian.” (paragraph 2)
d. “Research shows that learning and speaking another language positively affects the brain.” (paragraph 3)