Identify which examples constitutes valid consideration for purposes of determining whether a valid contract exists.

Question $9$ options:

Ronald saves a drowning swimmer named Vicki.$$ Vicki's grandmother promises to pay Ronald $$10,000\mathrm{.}00$ for his good deed.$$ Later, she refuses to pay.

I promise to pay you $$50,000\mathrm{.}00$ if you kill my ex$-$husband who murdered our dog.

None of these examples demonstrate valid consideration.

The famous tenor, Luciano Pasta agrees to sing the role of Rodolfo in Puccini's La Boheme for one performance only at Teatro all Scala for $$150,000\mathrm{.}00.$

Later, Luciano changes his mind and refuses to sing the role unless he is paid $$200,000\mathrm{.}00$ The manager mumbles in agreement just to get him on the stage!

The $$200,000\mathrm{.}00$ is therefore valid consideration.