In the graph below, the concentration of a particular pollutant in a lake is plotted over (alternate) days of a month in winter (average temperature $10^{\circ} C$) and a month in summer (average temperature $30^{\circ} C$).
Consider the following statements based on the data shown above:
- Over the given months, the difference between the maximum and the minimum pollutant concentrations is the same in both winter and summer
- There are atleast four days in the summer month such that the pollutant concentrations on those days are within $1$ ppm of the pollutant concentrations on the corresponding days in the winter month.
Which one of the following options is correct?
- Only i
- Only ii
- Both i and ii
- Neither i nor ii