Q:

A is the brother of B. B is the brother of C. D is the father of A. Based on these three statements, which of the following statements cannot be definitely true? 

• 1
  A is the brother of C
• 2
  C is the brother of A
• 3
  B is the brother of A
• 4
  B is the son of D
• 5
  A , B and C are D's children