I'm trying to store some information that describes which of a list is currently selected by the user.

For example:
Table: users
users_id
userName

Table: collections (a collection can have only one name)
collections_id
collectionName

Table: books (a book can have only one name)
books_id
bookName

Table: users_collections (one user can have many collections, but a collection can have only one user)
users_id
collections_id

Table: books_collections (a book can belong to many collections)
books_id
collections_id

I want to store which collection and book a user is currently viewing, and am not sure how to properly store it:

Option 1:
New table called currentselections:
users_id
currentCollectionID
currentBookID

Option 2:
Two new tables, currentBook & currentCollection:
users_id
currentcollectionID or currentBookID

Option 1 seems attractive to me, but I can't seem to find any good advice on this in any database design resources.

the difference between 1. and 2. is the difference between 3NF and 5NF (or is it 6NF?) and i don't think it matters

can a user look at a book that isn't in a collection? can a user look at a collection but not at a book in that collection?

it looks like user-book is 1-to-0-or-1, and user-collection is also 1-to-0-or-1, in other words, either is optional

so i would use 1. and allow NULLs