Which of the following individuals does not have the ability to enter a contract?

The individual who does not have the ability to enter a contract is a deceased person. Once an individual has passed away, they are no longer capable of entering into any legal agreements or contracts. The concept of contract law requires that parties involved be legally competent and living.

In contrast, an illiterate person can still enter a contract as long as they understand its terms and are capable of making informed decisions. An insane person may be able to enter a contract if they are not in a state of insanity at the time of signing, and their competency can sometimes be evaluated. An alien, or foreign national, can also enter into contracts in the U.S., provided they do not violate immigration laws and are of legal age and capacity.

Thus, the ability to contract is inherently lost upon death, making a deceased person the clear answer in this context.