Complete with who followed by the singular simple-past be-passive of select. Priya was the only one of the applicants ___ for the fellowship.
الإجابة الصحيحة
who was selected
الشرح
Who refers to the unique applicant identified by the only one, so the singular auxiliary was agrees with that antecedent. A plural auxiliary would treat the whole applicant group as selected and contradict the sentence's uniqueness claim.