"celebrate" Plural or Singular?

[Unregistered]

Girls Incorporated of New York City celebrate its graduates.

OR

Girls Incorporated of New York City celebrates its graduates.

Which is proper English?

 

[fromatto]

Girls Incorporated of New York City celebrate its graduates.

OR

Girls Incorporated of New York City celebrates its graduates.

Which is proper English?

The second one is correct.

The first one, as written, is wrong. However, you might say, 'GI of NYC celebrate their graduates'.