Determine whether the taxpayers in each of the following situations have realized taxable income:

a. Alexander inherited a tract of land from his uncle who died during the current year. A friend of Alexander's who is a petroleum engineer told him he thought there might be oil on the land. Alexander had the land surveyed, and an oil deposit worth an estimated $5,000,000 was discovered on the property.

b. Mickey was given two tickets to the World Series by a friend. Mickey sold the tickets for $500 apiece.

c. Hannah is the purchasing agent for Slim Diet Centers. Harold, a salesman who does considerable business with Hannah, gave her a set of golf clubs worth $750. Harold told Hannah that he was giving her the clubs to show his appreciation for being such a good friend throughout their business dealings.

d. Melanie's father died during the current year. She was the beneficiary of a $200,000 insurance policy on her father's life. She received the proceeds on August 1 and immediately invested in a bank certificate of deposit with a 9% annual earnings rate.