H4 EAD c26 category,which receipt number to be added

I am currently on H4 and my spouse got his I140 approved.Now while applying for EAD, it asks for receipt number of H1b spouse’s most recent form I-797 notice for form I-129, petition for a nonimmigrant worker.
I have a confusion which receipt number should I add
I-797 for I-129 or I-797 for I-140?

The phrase most recent is causing the confusion. It would be greatly appreciated if anyone can help me on that.

Thanks in advance!