单选题
Evidence came up {{U}}which{{/U}} specific speech sounds are recognized by babies as young as 6 months old.
【正确答案】
C
【答案解析】[分析] 结构应用
本句意为：六个月大的幼儿能够识别具体语音的证据已经有了。在本句中specific speech sounds are recognized by babies as young as 6 months old是前面evidence的同位语，因此应由that引导，答案应为C。