The answer to the question
The answer is the letter c.
763 divided by 4 is 190.75. 190.75 times 3 is 572.25.
It will take 8.2 x 10^20 electrons to have the same mass as one dust particle.
To get this answer, we divided the mass of the dust particle by the mass of the electron.
7.5 x 10^-10 divided by 9.1 x 10^-31 is 8.2 x 10^20