A69.1-g sample of h2o contains how many molecules of water?

  The  number  of  molecules   of   water   is calculated  as  follows

find the  moles of   water=  moles=mass/molar  mass

moles  =   69.1g/18 g/mol   =  3.84  moles
by  use of  Avogadro  law constant 
that  is  1  mole =   6.02  x10^23   molecules  what   about  3.84   moles  of  water

  the  molecules  of  water  =  (3.84   x   6.02  x10^23) = 2.312  x10^24  molecules

Well technically there are two correct answers b and d. but for you its probably b in general.good day sir/ma'am : ) (i know not gender)