Only 25 and 28 are functions.
A function must have only one y value per x value. For 26, the y value of 0 and multiple others have two different y values. For 27, all x values less than 0 have multiple y values.
In most cases, a private company is owned by the company's founders, management, or a group of private investors. A public company is a company that has sold all or a portion of itself to the public via an initial public offering.
Biased most likely means not random in this context. The actual definition is "unfairly prejudiced for or against someone or something"
