单选题 Safety officials have earnestly questioned whether the increased use of synthetic materials heightens the risk of fire.
A. cautiously B. severely C. accurately D. seriously

【正确答案】 D
【答案解析】[解析] D项的意思是“认真地”与“earnestly”的意思相吻合，A项“小心地”；B项“严重地”；D项“精确地”