$A$ speech signal of $3 kHz$ is used to modulate a carrier signal of frequency $1 MHz$,using amplitude modulation. The frequencies of the side bands will be

• A
  $1.003 MHz$ and $0.997 MHz$
• B
  $3001 kHz$ and $2997 kHz$
• C
  $1003 kHz$ and $1000 kHz$
• D
  $1.0 MHz$ and $0.997 MHz$