What Do You Want from Room When You Create a DAO

What do you want from Room when you create a DAO method and annotate it with @Update? Example:
@Dao
Interface MyDao {
@Update
Fun updateUsers(vararg users: User)
}

A) Room generates an implementation that inserts all parameters into the database in a single transaction.
B) Room modifies a set of entities, given as parameters, in the database. It uses a query that matches against the primary key of each entity.
C) Room removes a set of entities, given as parameters, from the database. It uses the primary keys to find the entities to delete.