Registration of a Child as British - Query

Hi All,

I got ILR recently , so i'm going to Register my son as a British Citizen (MN1), who is UK born & 12 months old.

We have traveled out of UK for holidays last year when is he was 4 months old , so i have got tier 2 dependent visa - BRP for my son , But its now expired last month along with me,

In online application there is question about BRP details .

Are you able to provide a biometric residence permit (BRP) card with this application? (Required)
This is a card with your name, date of birth, nationality and picture. It describes your entitlement to be in the UK. You might not have a BRP card. Select 'No, I do not have a BRP for my most recent leave' if you do not have this card.

I'm quite confused with the below options to select .

Yes

or

No, I do not have a BRP for my most recent leave.

Could you guys please clarify me and guide me which one to select.

Regards
DEV

Provide the old BRP

Thanks for your reply,
Regarding professional referee, My senior colleague who is a Principle Engineer ( holding Professional qualification) is ready to give reference , is that acceptable? he knows my son from his birth.
I have tried my GP, nurse health visitor none of them are interested to give there details.

Thanks
DEV

One of the referees must have dealt with your child in his/her professional capacity