This questions has Statement-1 and Statement-2. Of the four choice given after the statements,

This questions has Statement-1 and Statement-2. Of the four choice given after the statements, choose the one that best describes the two statements.

Statement-1 : Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals.

Statement- 2 : The state of ionosphere varies from hour to hour, day to day and season to season.