Which of the following is the correct statement for an electron?

• A
  $Electron$ is a particle having a negative charge of one unit and zero atomic mass.
• B
  $Electron$ is a particle having a positive charge of one unit and zero atomic mass.
• C
  $Electron$ is a particle having a negative charge of one unit and a mass of about $9.1 \times 10^{-28} \ g$.
• D
  $Electron$ is a particle having a negative charge and a mass of about $1.7 \times 10^{-24} \ g$.