Hello, I'm learning English as my second language.

I've got a test and wrote an answer to the question in which filling up a blank.

Q: In the heat of a debate, it is easy to lose your cool and attack the other side for having an opinion that is different from ____.

The correct answer is

1. yours

2. your opinoin

3. your own opinion

But my answer was "your own" and got a wrong mark.

I don't think "your own" is inappropriate in the blank.

What do you think?
"Your own" is perfectly reasonable.
All the choices are grammatically correct. So the question should ask for the best answer, not the correct answer. In a conversation between native speakers you would hear only the possessive pronoun "yours." A speaker would not repeat the antecedent "opinion," because it is clear what is meant.
Students: We have free audio pronunciation exercises.
Thank you for your explanation.

But I was required to fill in the blank, not to choose the best from selective examples.

Now that native speakers usually don't repeat the antecedent, my answer "your own" can also be regarded correct?

I want to be sure that "your own" can be filled in the blank.
"your own" is fine in the blank, but it was not one of the three choices given.
There weren't three choices given -- there was jut a blank given, and three acceptable answers listed.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Oh OK.

The OP's description gave a list of 3 choices, so I assumed it was part of the question on their test.
AnonymousThank you for your explanation.

But I was required to fill in the blank, not to choose the best from selective examples.
Now that native speakers usually don't repeat the antecedent, my answer "your own" can also be regarded correct?
I want to be sure that "your own" can be filled in the blank.
Yes, as I said, "your own" is perfectly fine, and it's a formulation I would be unsurprised to see a native speaker use.