أَعَمْرًا عَرَفْتَ
Was it ʿAmr whom you recognised?
Fronting may create salience or a sense of distinction, but it need not automatically express an exhaustive restriction. In a question, the immediate rhetorical aim may simply be to spotlight the constituent whose identity is unknown.
If the speaker neither excludes nor affirms any other person, “A-ʿAmran ʿarafta?” does not by itself entail “You recognised ʿAmr and no one else.” Restriction requires suitable contextual grounds.