PwC was one of the firms that extended me an offer.

Unless you're an experienced hire, they won't ask you what industry you want to work in.  It's something to choose after you get an offer, but it's not something to bring up in an interview.  There are better things to talk about. 

The weakness question is a cheap, unskilled-interviewer tactic, and is a trap.  The interviewer is saying, "Gimme some reasons why I shouldn't hire you (since I can't hire everyone, make my job easier and gimme a reason to disqualify you so I don't have to come up with one on my own)."  Now you really think you should give an honest weakness of yours and put yourself in a negative light, in an interview of all places?! Just hand them an excuse not to hire you by presenting your character flaws?  You think you're disrespecting the question by not giving them a true fault?  No.  Bad thinking.  The interviewer won't say, 'gimme a character flaw', but why do you assume this is what 'weakness' implies?  A weakness could be a deficiency, right?  Which should only be in comparison to everyone else who's interviewing for the position.  So what could the other candidates have over you?  More experience, better grades, etc.  Maybe some of them were interns, and usually most interns get hired on, so obviously experience helps, even for the entry-level positions.  I'd answer that you don't have direct work experience as an auditor or worked in accounting before, but you did well in these classes and you know the position requires you to work hard and in teams and here's how you've demonstrated that in the past, so here's how you could quickly overcome your lack of experience. 

Otherwise, never, ever give them any character flaws.  The interviewer is not your psychologist or your friend. 

Yeah, wrong.  This doesn't have to be a Catch-22 question.

If you're flat-out asked for a weakness, I'd answer as I described above.  If they give you a more specific question, like give me a time when you failed at something or made a mistake and why, they want to see how you overcame and remedied - that is the 'reflection' being sought by the interviewer.  Don't give them examples of your efficiency being hampered by your perfectionism, or your poor time-management skills from taking on too much work.  This still leaves a negative impression of you, even though yes, a specific question was asked.  And whatever your response, always follow up with how you learned and overcame and improved.