should the question inform if it refers to a female ?
No. The possessive (तेरी in this case) always refers to the thing being possessed. Here, since किताब is a feminine noun, तेरी is your choice. तेरा is used for singular masculine nouns, and तेरे is used for plural masculine nouns.
No it can be either male or female
Why is "your" feminine? Is it because "book" is feminine? Would "your" stay in the female form even if I am speaking to a man in this situation?
Yes. When dealing with possessive pronouns, the pronoun has to match the gender (and number) of the object that belongs to him/her/it.
Is it incorrect to translate this as "This book is yours"?
why "Theri" ??
I think Kitaab is feminine
How come my answer come wrong