Explanation:

- You are the ____________ to the throne and should behave in such a manner.

- This sentence suggests someone is set to inherit a position of power or responsibility, typically a monarchy.

- Option 1: hair

- "Hair" refers to the strands growing on a person's head or body.

- It's irrelevant in the context of inheriting a position.

- Option 2: here

- "Here" indicates a location or position.

- It's unrelated to the concept of succession.

- Option 3: hare

- "Hare" is a type of fast-moving mammal.

- Doesn't fit the context of inheriting a throne.

- Option 4: heir

- "Heir" means a person legally entitled to inherit a position or office after someone else's death.

- ?? This is the appropriate word for the context of the sentence.