Technically, F1, F2, H1, H4 and J type visa holders are not authorized to work in US. Some big companies like IBM will list the visa type out so you will not be confused. I would say if the company are well known and big, you can answer the question pretty simply (i.e. NO) if they did not specify the applicant must be citizen or gc. Most of them will apply H1b and gc for you in future. In case of small company, you should explain to hiring manager and HR how are you going to deal with the visa problem (opt, h1b...). Some of them just don't want to be bothered with all the paper works.