ashutoshsh
hey!
isnt the refernce of "it" in optionC unclear. "it" is for mexican war or for tax? ...
or may b we cn say it's refernce is clear bcoz "taxes" are plural and only singular term is war... m not sure

Dear
ashutoshsh,
I'm the author of this question and I am happy to respond.
First, my friend, I am going to caution you. GMAT Club is one of the first steps you are taking toward the GMAT, so it is one of the first steps you are taking toward your entire professional life. The people here on GMAT Club may one day be your employers, your managers, your colleagues, your customers, your partners, your competitors, etc. You don't know where you may meet someone again in the global economy. Furthermore, in this life, you only get one chance to make a first impression, and several psychological studies have demonstrated that first impressions have massive influence on later interactions. In the business world, it is always worthwhile to be as professional as possible and, accordingly, to put your best self forward at all times. Your post here is extremely casual, full of slang and abbreviations and spelling errors. Such language would be fine in a text to your friends or a post on social media, but GMAT Club is NOT a social media site. This is a serious professional site where candidates can get valuable aid in preparing for the GMAT, applying to business school, etc. I would strongly urge to rise to the highest standard of language of which you are capable, each and every time you post on GMAT Club. This is not a place to experiment with whether you are an adult. This is an adult community, and regardless of whether you realize it, you will be evaluated according to adult and professional standards. I wanted to caution you, my friend, because I am concerned for you. I want you to be seen in the best possible light. If you always strive to do your best, you will have far fewer regrets in life. Furthermore, if you have ambitions to excel on the GMAT, you would be well advised to strive for excellence in every aspect of your life.
In answer to your specific question, yes, because "
it" is a singular pronoun, it's absolutely clear that it refers to the only singular noun that precedes it in the sentence, the
Mexican-American War. Whether a pronoun is singular or plural is always a crucially important delimiter in determining its antecedent.
Does all this make sense?
Mike