Which statement is false?

Every binary tree has at least one node
  • Every non-empty binary tree has exactly one root node
  • Every node in a binary tree has exactly two children
  • Every non-root node in a binary tree has exactly one parent

Look carefully at the definition for a binary tree.

It states that every binary tree is either empty, or it has a root node and two binary trees as children.

So, every binary tree node has two children, but not every binary tree has a node.