While freedom of contract typically prevails, sometimes courts will refuse to enforce a contract because it is "unconscionable," particularly if it is too one$-$sided and involves unequal bargaining power between the parties. Which of the following contracts would a court likely refuse to enforce because it is unconscionable?

a$.$ When he is $12$ years old, Marc agrees to trade his Michael Jordan rookie card, then worth $$1,800,$ to his best friend Joel, also $12$ years old, in exchange for an error baseball card that accidentally contains the word "hoser" on the end of the baseball bat, which at that time was valued at $$1.$

b$.$ When he is $40$ years old, Marc agrees to trade his Michael Jordan rookie card, then worth $$40,000,$ to a local jeweler for a pair of rare diamond earrings that his wife, Candy, has always coveted, then worth $$30,000.$

c$.$ After developing an Internet search engine that has the potential to compete with Google, a Coastal Carolina professor nearing the end of his teaching career hires a lawyer to negotiate the sale of his search engine for $$500,000$ to a group of investors, after which the search engine becomes a huge success, making the company hundreds of millions of dollars.

d$.$ After developing an Internet search engine that experts in the industry believe would compete with Google, a Coastal Carolina University sophomore develops a rare brain disease that interferes with his cognitive abilities and then contracts with a wealthy Russian oligarch to sell the search engine to his company for $$200,000,$ after which the search engine becomes a huge success, making the company hundreds of millions of dollars.