Inheritance tax – marriage exemption, annual exemption

Dear tutor,
I have a question related to inheritance tax for the following question:

“On 1 July 2022, Daniel made a cash gift of £2,500 to his sister.
On 1 May 2023, he made a cash gift of £2,000 to a friend.
On 1 June 2023, he made a cash gift of £50,000 to a trust. Sameer has not made any other lifetime gifts.
In respect of Sameer’s cash gift of £50,000 to the trust, what is the lifetime transfer of value for inheritance tax purposes after taking account of all available exemptions?

Solution:
£
Transfer of value: 50,000
Annual exemption
– 2023/24 (£3,000 – £2,000) = (1000)
– 2022/23 (£3,000 – £2,500) = (500)
Gross chargeable transfer : 48,500 ”

Why the answer takes only the annual exemption in the case of the gift to the sister? I thought, we always have to take into account marriage exemption first.

So, in the case of his sister, that exemption should be £1,000 (marriage exemption for anyone else), which leaves £1,500 for annual exemption; therefore the remaining annual exemption should be: £(3,000-1,500) = £1,500.

However in the solution, the remaining annual exemption is: 2022/23 (£3,000 – £2,500) = (500), which means they do not take into account of marriage exemption at all.

Thank you for your help!