The correct option is A.
Fluorescent lamps have many advantages over incandescent lamps and the options given in B, C and D are part of these advantages. The option given in A is a disadvantage and not an advantage. This is because, as a result of operating at an higher temperature, it will gives out and radiate more heat.
M= gpe / gh
G= gpe / mh
H=gpe / mg
The temperature where vapour pressure equals atmospheric pressure is called BOILING POINT. This vapour pressure increases with rise in temperature. Also boiling point is different for different liquids. Hope I cleared your doubt...
To convert from newtons to kg in earth gravity, simply divide by 10 (or 9.8 if being specific). 645N = ~64.5kg