Two coaxial solenoids of different radii carry current $I$ in the same direction. Let $\vec{F}_1$ be the magnetic force on the inner solenoid due to the outer one and $\vec{F}_2$ be the magnetic force on the outer solenoid due to the inner one. Then:

• A
  $\vec{F}_1$ is radially inwards and $\vec{F}_2 = 0$
• B
  $\vec{F}_1$ is radially outwards and $\vec{F}_2 = 0$
• C
  $\vec{F}_1 = \vec{F}_2 = 0$
• D
  $\vec{F}_1$ is radially inwards and $\vec{F}_2$ is radially outwards