Jan promises Eli $$4,000$ for one of his original paintings on the condition that she receives $$1$ million from her mother's will.

Select one:

a$.$ Jan's promise is legally sufficient unless Jan knows she cannot inherit the $$1$ million.

b$.$ Jan has made an illusory promise.

c$.$ Jan has made a conditional promise which is not sufficient to form consideration.

d$.$ Jan's promise is legally inadequate and the courts will therefore not enforce it$.$