Carol and Bob divorced on January 4, 2017. Their divorce decree required Carol to pay Bob alimony pursuant to the written divorce decree, in cash or by check. If Bob should die, the alimony payments continue for another 10 years after death to a trust established for the care of Bob's parents and disabled brother. In 2017 she paid $12,000 to Bob, $12,000 in 2018, $12,000 in 2019, and $12,000 in 2020. How much income must Bob recognize in 2020?

$0

$48,000

$12,000

$6,000