单选题 Naturally occurring chemicals cannot be newly patented once their structures have been published. Before a naturally occurring chemical compound can be used as a drug, however, it must be put through the same rigorous testing program as any synthetic compound, culminating in a published report detailing the chemical"s structure and observed effects.
If the statements above are true, which of the following must also be true on the basis of them?

A、 Any naturally occurring chemical can be reproduced synthetically once its structure is known
B、 Synthetically produced chemical compounds cannot be patented unless their chemical structures are made public
C、 If proven no less effective, naturally occurring chemicals are to be preferred to synthetic compounds for use in drugs
D、 Once a naturally occurring compound has been approved for use as a drug, it can no longer be newly patented
E、 A naturally occurring chemical cannot be patented unless its effectiveness as a drug has been rigorously established

【正确答案】 D

【答案解析】[解析] 本题为归纳题型，注意把握逻辑层次结构。本题的推理为：天然产生的化学物质合成物当药物→在出版的报告中详细说明药品的结构一不能取得专利。(D)与此推理完全吻合，所以(D)正确。