Reflexive pronouns<span> are </span>pronouns<span> that refer back to the subject of the sentence or clause. They either </span>end in<span> –self, as in the singular form, or –selves as in the plural form.</span>
The answer would be "I ate lunch near the river." The difference is there is no "was" making the sentence longer. Active sentences are clearer and shorter than a passive sentence (the other options are passive.)
