The Essential Requirement for Different Businesses to Be "Related" Is

The essential requirement for different businesses to be "related" is that

A) their value chains possess competitively valuable cross-business relationships.
B) the products of the different businesses are bought by much the same types of buyers.
C) the products of the different businesses are sold in the same types of retail stores.
D) the businesses have several key suppliers in common.
E) the production methods that they employ both entail economies of scale.