( A ) Comparatively more permeable of $K^+$ ions and nearly impermeable to $Na^+$ ions
( B ) Comparatively more permeable to $Na^+$ ions and nearly impermeable to $K^+$ ions
( C ) Equally permeable to both $Na^+$ and $K^+$ ions
( D ) Impermeable to both $Na^+$ and $K^+$ ions