Consider two circuits, $(A)$ and $(B)$, each having two resistors. One of them has a positive temperature coefficient of resistance, $+\alpha$, while the other one has a negative temperature coefficient of resistance, $-\alpha$. The current through these circuits are denoted by $I_A$ and $I_B$. At initial temperature, the resistance of the two resistors is $R_0$. As the temperature is increased, the correct option that describes the variation of current in these circuits is:

• A
  $I_A$ remains constant while $I_B$ increases
• B
  $I_A$ decreases while $I_B$ increases
• C
  $I_A$ increases while $I_B$ decreases
• D
  both $I_A$ and $I_B$ remain constant