A slice of pizza is:

• A. Rival
• B. Non-rival
• C. Non-excludable
• D. Both (a) and (c)

Answer: (A)

Verified step by step guidance

1. Understand the concept of 'rival' and 'non-rival' goods. A rival good is one where consumption by one person diminishes the ability of another person to consume it. A non-rival good is one where consumption by one person does not affect the availability for others.
2. Consider the nature of a slice of pizza. If one person eats a slice, it is no longer available for others. This characteristic makes it a rival good.
3. Understand the concept of 'excludable' and 'non-excludable' goods. An excludable good is one where it is possible to prevent people from accessing it if they do not pay for it. A non-excludable good is one where it is difficult or impossible to prevent people from using it.
4. Consider the excludability of a slice of pizza. Since you can prevent someone from eating a slice unless they pay for it, it is an excludable good.
5. Based on the definitions and characteristics, determine which options correctly describe a slice of pizza. Since it is both rival and excludable, it does not fit the definitions of non-rival or non-excludable.