What we want is an environmentally friendly car, especially is good on gas.
A. one
B. one which
C. which
D. one that
网友回答
A. one
B. one which
C. which
(答案→)D. one that
解析：one 作an environmentally friendly car的同位语，同时one 又是后面定语从句的先行词，定语从句中缺少主语，one 是不定代词，所以只能使用关系代词that，故选D。