A glass vessel is filled up to 3/5th of its volume by mercury. If the volume expansivities of glass and mercury be `9xx 10^(-6)//^(@)C` and `18xx10^(-5)//^(@)C` respectively, then the coefficient of apparent expansion of mercury is
A. `17.1xx10^(-5)//^(@)C`
B. `9.9xx10^(-5)//^(@)C`
C. `17.46xx10^(-5)//^(@)C`
D. `16.5xx10^(-5)//^(@)C`