Every title, with the author and claimant the application will name. A title's protection for statutory damages starts on the effective date of its registration — the day the Copyright Office receives a complete application — unless a published title is registered within three months of first publication.
A title goes out only once it is in a filed application. Registered before release, as part of an unpublished group, every infringement from the first day is covered — at $85 for up to ten titles, the cheapest moment there will ever be.
A group of unpublished works takes up to ten titles, all unpublished, all the same type, all by the same author with the same claimant. Tick them, type the service request number the Copyright Office gave you, and file.
A title already published without a registration keeps statutory damages and attorney's fees for infringement from its first day only if it is registered within three months of first publication. After that, only infringement begun after registration qualifies.