The plates of a capacitor are charged to a potential difference of $320 \, V$ and are then connected across a resistor. The potential difference across the capacitor decays exponentially with time. After $1 \, s$ the potential difference between the plates of the capacitor is $240 \, V$,then after $2 \, s$ and $3 \, s$ the potential difference between the plates will be:

• A
  $200 \, V$ and $180 \, V$
• B
  $180 \, V$ and $135 \, V$
• C
  $160 \, V$ and $80 \, V$
• D
  $140 \, V$ and $20 \, V$