Assuming my understanding of suffixes is correct it seems like ördeklerim, on its own, could either be the possessive or the copula. In this sentence the possessive makes more sense than the copula (I am ducks) but is there a way to know for sure which one is being used in other sentences?
Can we get explanation why the answer "The ducks are mine" is not correct?
"Ördekler benim ördeklerim." Translation: The ducks are my ducks.
Let's look at the Turkish question:
Plural noun - "Ördekler" "the" ducks.
Benim - Ben - "me" & "-im" possessive pronoun suffix for - "are mine."
Ördeklerim - ördek - "duck" ördekler - "the" ducks & ördeklerim. The -im suffix signifies ownership - possession.
The ducks are my ducks. The Turkish question has two plural words. The repeated plural word ducks for "subject" & "object."
"My" & "mine" are pronouns & determiners in English. The Turkish question does not have a verb as such & "ördeklerim" is the only way to recognise /distinguish ownership.
I still believe personally that your answer is correct.
If I am wrong regarding the verb then it is integral to the word - ördeklerim - "my ducks."
EDITED - (14/10/2019) Can we get explanation why the answer "The ducks are mine" is not correct?
"The ducks are mine" - Ördekler benim.