I prefer writing _______( in/by) ink

An ink pen, with a cylindrical barrel of diameter 2 cm and height 10.5 cm, and completely filled with ink, can be used to write 4950 words. How many words can be written using 400 ml of ink ? (Take 1 litre = 1000 cm^(3) )

An ink pen,with a cylindrical barrel of diameter 2cm and height 10.5cm, and completely filled with ink,can be used to write 4950 words.How many words can be written using 400ml of ink? (Take 1litre = 1000cm^(3))

_______ is used for the manufacture of priting ink .

("I prefer")/(a) ("this book")/(b) ("than that one")/(c). ("No error")/(d)