Last Year Rebecca Set Aside $5000 Pretax Dollars for Child

Last year Rebecca set aside $5000 pretax dollars for child care in a flexible spending account.She only used $3200.What happened to the remaining $1800?

A) She received a lump sum payment of $1800 in her first January paycheck.
B) It reverted to her employer.
C) She had to pay taxes on the amount before it was added back to her income.
D) She transferred it to her medical care account.
E) It stays in the account to be used this year, a rollover.