The correct answer is: [I], [II] and [III].
All three statements describe characteristics of a firm:
- [I] is true because a firm indeed represents a unit that employs factors of production to produce goods and services.
- [II] is true as firms can take different forms (e.g., sole proprietorships, partnerships, corporations).
- [III] is also true because firms largely determine how goods and services are produced, which includes decisions about production techniques, labor, and other factors.
Thus, all statements are characteristic of a firm.