一般情况下，下列哪种燃气的爆炸下限最低，最容易发生爆炸（）

A.天然气

B.液化石油气

C.人工燃气

D.沼气

All else being equal, an increase in the price of one product will most likely cause the demand curve of the product's supplement to:（）

A. Remain unchanged.

B. Shift upward and to the right.

C. Shift downward and to the left.