Question

Which of the following best explains the outcome of the 1828 presidential election?

Answer 1

John Quincy Adams was an unpopular president, and Andrew Jackson ran a strong campaign.

Answer 2

Before the election the previous president was John Quincy Adams, but Andrew Jackson won.

Based on this information we can reject the following options:
John Quincy Adams was a popular president, and Andrew Jackson ran a poor campaign. (else he wouldn't win)
John Quincy Adams was such a popular president that Andrew Jackson lost despite running a strong campaign

Now, John Quincy Adams was not a very bad president, but Andrew Jackson won because of his campain:

the correct answer is:
John Quincy Adams was an unpopular president, and Andrew Jackson ran a strong campaign.