Right option is (a) True
To explain I would say: In pycnometer method, the water content is calculated from,
\(w=[(\frac{M_2-M_1}{M_3-M_4})*(\frac{G-1}{G})- 1]× 100\)
Where, M1=Empty mass of pycnometer with cap
M2= mass of pycnometer + 200g to 400g of soil sample
M3= mass of pycnometer +soil sample + water till hole of conical cap
M4= mass of pycnometer + water till hole of conical cap
G=Specific gravity.