3
From the bar graph, characteristic X has the highest value for Mercury.
Using the provided reference tables, the eccentricity of orbit of Mercury is
higher compared to that of other planets.
The values for the eccentricity of orbit given in the tables exactly match
those in the bar graph, i.e.,
Mercury : 0.206 ; Venus : 0.007 ; Earth : 0.017 ; Mars : 0.093 ;
Jupiter : 0.048 ; Saturn : 0.056 ; Uranus : 0.047 ; Neptune : 0.009
So, characteristic X is eccentricity of orbit.

3
From the bar graph, characteristic X has the highest value for Mercury.
Using the provided reference tables, the eccentricity of orbit of Mercury is
higher compared to that of other planets.
The values for the eccentricity of orbit given in the tables exactly match
those in the bar graph, i.e.,
Mercury : 0.206 ; Venus : 0.007 ; Earth : 0.017 ; Mars : 0.093 ;
Jupiter : 0.048 ; Saturn : 0.056 ; Uranus : 0.047 ; Neptune : 0.009
So, characteristic X is eccentricity of orbit.