Question: What type of industry does Jeff Tremaine and Robert Mulligan have in common?
Sentence (from "Comet (magazine)"): The young Isaac Asimov, visiting Tremaine in "Comet"' s offices, was alarmed when Tremaine asserted that anyone who gave stories to competing magazines for no pay should be blacklisted; Asimov promptly insisted that Donald Wollheim, to whom he had given a free story, should make him a token payment so he could say he had been paid.
Relevant evidence: No