Inheritance tax

Hi,
I don’t understand why the sister does not suffer any tax in this question? Could you please kindly explain this to me?
Thank you.

Melvin died on 6 March 2018 leaving an estate worth £2,000,000. His estate included a holiday home in the UK worth £400,000 which he left to his sister. He left the rest of his estate to his daughter and appointed a friend to act as executor.

For each of the following individuals, select whether they will pay the inheritance tax due on the estate, suffer the inheritance tax payable on the estate, or neither. It is possible to select more than one individual for the same answer.

Pays tax
Suffers tax
Neither pays nor suffers tax

Sister
Daughter
Executor