In a library database, there are entities for "Book" $($E$1)$ and "Author" $($E$3).$ What is the likely relationship type between Book and Author?

a$.1-1($One$-$to$-$One$)$

b$.N-1($Many$-$to$-$One$)$

c$.N-M($Many$-$to$-$Many$)$

d$.1-$N $($One$-$to$-$Many$)$