Step basis on inherited property

I hope this is a quick question. This is for a Trust. I'm the trustee.

 

My sister died 12/28/23

Her condo was sold 12/10/24. Let's say for $500k

 

The fair market value stayed about the same from time of death until the property was sold. What do i enter on the form for the stepped up basis? I have been given 2 different answer for the same question. 

 

Do i enter $0 on the form, or $500k on the form?