单选题 You are exposed to obtrusive ads that ______ seemingly from nowhere even when you are disconnected from the Net, and your personal information is gathered and sent off without you being aware of it.

【正确答案】 D
【答案解析】[解析] 本题中，D项“pop up突然出现”符合题意。其他三项“A项size up评估……的大小；B项dwindle away减少，缩小；C项conjure up用魔法召”都不正确。因此D项为正确答案。