You should use “is it,” not “it is.”

Sorry for the multiple posts : italki would not take this in one chunk. I don't know why :( Update - I put inverted commas around as, and the software blocked my post. I suppose it is listed as a bad word when quoted, for reasons I don't understand.

Your 2 is mostly good - the inversion is right for how you have the word order - but it could be a little clearer. Your use of - as - is correct, but a little hard to follow at first reading. And your positioning of the verb after "not only" creates a need for a balancing verb in the "but also" clause. If the verb chosen is going to be the same, this creates unpleasant (but not wrong) duplication. Often, we can move the verb in front of "not only" to avoid the duplication. So you might consider: " I consider this to be one of the best policies adopted by the authorities, as IT IS our moral duty not only to protect such animals, but also to maintain ecological balance."

c: "

1 ."