It can be inferred from the passage that _

问题单项选择题

It can be inferred from the passage that ______

A．vanillin is easier to synthesize than benzaldehyde

B．not all synthetic flavors are harmless

C．in general, the less components there are in a fragrance, the harder it is to synthesize

D．synthesized substances must be tested for safety only if they are used in food

答案

参考答案：B

解析：[分析] 推断题型。见第三段第一句：Many of the chemical compounds…and are as harmless or harmful as the natural substances．由此推断出：有些化学合成物(其中也包括香料)与其自然界存在的物质一样是无害的，有些则是有害的。因此选项B为答案。