Which of the Following Statements Regarding Functional Groups and Families

Which of the following statements regarding functional groups and families is TRUE?

A) A group of organic compounds forms a family if they share the same characteristic carbon atom backbone called the functional group.
B) A group of organic compounds forms a family if they share the same characteristic atom or a group of atoms called the functional group.
C) A group of organic compounds forms a family if they differ by one CH group, called the functional group, in their structure.
D) A family of organic compounds are all structural isomers with the same molecular formula called the functional group formula.
E) A family of organic compounds is composed of all isomers that have the same molecular formula and share the same characteristic atom or a group of atoms called the functional group.