Several students from your economics class are discussing the differences between private and public goods. Which of the following students correctly understands the differences? Select one: A. Karen: "I am pretty sure that public goods are not excludable but are rival in consumption." B. Theo: "I seem to recall that consumers can easily be excluded from consuming public goods and that they are also nonrival." C. Xiaojie: "I remember the professor saying that people can be excluded from consuming public goods and that their consumption of a public good does detract from anybody else's consumption." D. Fran: "According to the textbook, all public goods are non-excludable and non-rival in consumption