Which of the Following Situations Involves the Creation of a Contractually

Which of the following situations involves the creation of a contractually enforceable promise?

A) Suneeta promised to pay $5000 to a firefighter who responded to a routine call to extinguish a fire at her house.
B) Suneeta promised to pay $500 to her father for a birthday present that she had received from her parents two weeks earlier.
C) Suneeta had a contract with a construction company to build a deck in her backyard.Halfway through the project, the cost of materials suddenly increased.Although the original agreement did not require her to do so, Suneeta agreed to pay an additional $2000 to the construction company to off-set the additional expenses that it would encounter in the remainder of the project.
D) Suneeta borrowed money from a bank.Under the terms of that agreement, she was required to pay the bank $10 000 cash on June 1.On May 28, she explained to the bank that she would not be able to pay the full amount on schedule.On the same day, she also persuaded the bank to accept a cheque for $7500 in satisfaction of the full debt.
E) Suneeta's brother, Arvid, had long promised that he would pay $10 000 to her when she turned 21.She was always skeptical, but a few weeks before her 21st birthday, she wanted to be sure that he would honour his promise.Suneeta therefore persuaded Arvid to write his promise on a piece of paper, and then she added her signature and seal to that document.