Chris Irwin, who lives outside London, was irked by the third multiple-choice question, which asked what “incentive” translators would prefer, with five nonmonetary choices including an upgraded LinkedIn account and none (“because it’s fun”). Mr. Irwin checked a sixth choice, “Other,” typing in that he would prefer cash. In a phone interview, Mr. Irwin said he was surprised that LinkedIn “would have the effrontery to ask for a professional service for free.”