—Is that the small town you often refer to?

—Right, just the one____ you know I used to work for years. [ ]

A. that    

B. which

C. where  

D. what

下列化学方程式完全正确的是（　　）

A．天然气燃烧              CH₄+2O₂═CO₂+2H₂O

B．处理污水中的硫酸        Ca（OH）₂+H₂SO₄═CaSO₄+H₂O

C．二氧化碳气体的检验      CO₂+Ca（OH）₂═CaCO₃↓+H₂O

D．稀硫酸除铁锈            2H₂SO₄+Fe₂O₃═2FeSO₄+2H₂O