In economics, what does the term substitutes mean? Give an example of substitutes used in agriculture.
a) Substitutes are goods that are complementary to each other. Example: Coffee and sugar
b) Substitutes are goods that are unrelated to each other. Example: Tea and coffee
c) Substitutes are goods that can be used in place of each other. Example: Margarine and butter
d) Substitutes are goods that are only used in combination with each other. Example: Bread and jam