A mixture of `C_(4)H_(8)` and `C_(2)H_(4)` was completely burnt in excess of oxygen yielding equal volumes of `CO_(2)` and steam. Calculate the percentage (by volume ) of the compounds in the original mixture:
A. 25% `C_(4)H_(8)` and 75% `C_(2)H_(4)`
B. 30% `C_(4)H_(8)` and 70% `C_(2)H_(4)`
C. 75% `C_(4)H_(8)` and 25% `C_(2)H_(4)`
D. 50% `C_(4)H_(8)` and 50% `C_(2)H_(4)`