Which sentence from the passage is an example of an opinion disguised as a fact? Select one:

a.
If you're like most Americans, it's been a while. (paragraph 1)

b.
Postal service in the United States dates back to 1775 . . . (paragraph 2)

c.
Deliveries took weeks, if not months. (paragraph 2)

d.
Since 2007, the total volume of all mail has dropped 25 percent . . . (paragraph 6)