Solution

The correct answer is 2n - n

EXPLANATION:

• A binary tree allows for a maximum of two child nodes per parent node.
• The formula (2ⁿ - n) can be used to ascertain the number of different binary trees that can be drawn given 'n' number of nodes.
• As an example, when 'n' is equal to 1, applying the formula yields (2¹ - 1), which equals 1.
• As an example, when 'n' is equal to 2, applying the formula yields (2² - 1), which equals 2.
• As an example, when 'n' is equal to 3, applying the formula yields (23 - 1), which equals 5.
• Therefore, when 'n' nodes, we can draw (2n - n) unique binary tree.

Mistake PointsAbove question data is ambiguous so official answer key drop this question. We have updated the question.