Kellogg Applicants from North America, HELP!

petron12

     I thought I am exempt from TOEFL since I have completed a graduate degree in the U.S. ,but got an email from Kellogg asking for the verification of one of these three:
      Language of instruction in undergraduate is english
      US citizen or permament residence.
     I am holding a working visa, does that meant I have to take TOEFL? It's already too late to do this. Can you shed some light on this situation. So many thanks.