单选题 The old town has narrow streets and small houses ______ are built close to each other.
【正确答案】 D
【答案解析】[解析] 分析句子结构可知,先行词“narrow streets and small houses”在定语从句中充当主语,所以用关系代词“that”引导。故选D项。关系副词“where”表示地点,作地点状语。