The lower and upper fixed points of a mercury-in-glass thermometer are marked Y and 180mm respectively. On a particular, the mercury meniscus in the thermometer rises to 45mm. If the corresponding reading on a scale is 10o, calculate the value of Y.

A. 4mm
B. 18mm
C. 30mm
D. 135mm
E. 450mm

Correct Answer: Option C

C. 30mm