What relied on the outdoor use of sunlight/daylight to expose light sensitive paper

Which function of nonverbal communication is at work? trey was planning a surprise party for lynn, but when she asked him why they couldn't go out on friday, trey shifted his eyes, coughed, and stuttered when he said he already had plans. what did trey's nonverbal communication do for lynn? clarify the relationship regulate the interaction increase persuasive power reveal discrepancies manage impressions