I'm reading a book and have come across this sentence
アニーが指さしているのは、一本のなわばしごだった。
I know this sentence translates to something like
Annie was pointing to a long rope ladder.
But what I truly don't understand is what does the だった at the end modify? Is it modifying アニーが指さしている (Annie pointing) like I believe?
Or is it really modifying 一本のなわばしご (rope ladder)? And the translated sentence is more like
Annie pointed to what was a long rope ladder