This is a tough question because both options look pretty good. My recommendation would be to answer depending on the position you are applying for. For example, if you are applying for a type of analyst or upper management position, then anticipating a problem would be more useful. However, if you are applying to be a nurse for a hospital emergency room, then reacting to a problem well is stronger.
The answer gets stronger with examples, so if you have experienced something that you can explain, feel free to use include it in the answer. Also, if you are unsure about how to say it, remember that you can ask us.
Learn English speaking much FASTER by downloading the TalkEnglish Offline Package and submerge yourself with over 8,000 audio files and over 800 pages of lessons! Then you can study without Internet connection and also listen to audio files using your MP3 player at any time. Go to the English Download page and download today!