Atomic radii of the noble gases are larger than the precedent elements of the same periods because :

The correct option is C)

Noble gases have fully filled outer shells due to which their radius is expressed as Vander Waal's radius which represents the overall size of the atom which includes its valence shell in a non-bonded situation. And since valence electrons are completely filled therefore there are interelectronic repulsions, thus their size is larger than the precedent element.