Sentence 1: The concept of magnetically levitated trains was first identified at the turn of the century by two Americans, Robert Goddard and Emile Bachelet.
Which of the following options PROPERLY rewrites sentence 1?

This option is the only option that places the names of the two Americans by \u201CTwo Americans.\u201D The other options all separate the names of the two Americans from the description of where they are from, which is a grammatical error. The proper use would be: \u201CTwo Americans, Robert Goddard and Emile Bachelet ...\u201D or Robert Goddard and Emile Bachelet, two Americans, ...\u201D