Which sentence has an unclear or missing pronoun antecedent?

1 i want to visit nepal because the landscape will be amazing to you.

2 this area is famous for it's changes in weather.

3 ane writes her own mystery stories.

4 todd has a sister, and she is 15.

1 I want to visit nepal because the landscape will be amazing to you.

This sentence doesn't work. The pronoun you at the end does not work with the subject, I. The speaker says he wants to visit Nepal. He gives the reason that the landscape is amazing to "you". Well, if the landscape is amazing to someone else what does that have to do with him visiting Nepal? It should say that the landscape will be amazing to "me" so that it refers back to I as the subject. The other options are all correct. It is the correct antecedent for area. Her is the correct antecedent for Anne. She is the correct antecedent for Todd's sister.

Which sentence has an unclear or missing pronoun antecedent?

The correct answer is 2 this area is famous for it's changes in weather.

In number 2 the pronoun that refers to "this area" is incorrect because instead of using the subject pronoun "it" plus the verb to be "is", it should have been used the possessive adjective "its". The pronoun antecedent "it's" do not replace "this area" properly, it changes the meaning of the sentence completely. They do not agree in terms of possession, as "this area" refers to "it" and the rest of the sentence demands a use of a possession not of a subject pronoun and the verb to be, this wrong use splits the sentence into two, breaking the meaning as well.