The magazine set out to launch its most ambitious poll ever in 1936. Over 10 million postcards were mailed to Literary Digest subscribers, people on automobile registration lists, and names in telephone directories, of which 2.4 million were returned. The Literary Digest issued its predictions in an article boasting that the figures represented the opinions of "more than one in every five voters polled in our country" scattered throughout the forty-eight states. The results indicated that Republican candidate Alfred Landon would defeat Franklin Roosevelt, receive 57 percent of the popular vote, and carry thirty-two states in the Electoral College. Roosevelt won by a landslide, commanding 61 percent of the popular vote and winning in all but two states. —From Saylor. org's "Understanding Diverse Populations and Public Opinion," Comparative Politics, 2012

Which of the following errors in polling is this passage describing?

The questions in the poll were not open-ended.
The sample was not selected randomly.
The sample size was not large enough to be reliable.
The question wording used in the poll was confusing.