Which of the following statement is correct?

• Satellite transponders use a higher frequency for reception of radiation from earth stations and lower frequency for transmission to earth stations.
• Satellite transponders contain a device that echos the radiation without change from one point on earth to another
• Satellite transponder contain devices that transform the message sent from one location on earth to a different code for transmission to another location
• satellite transponders us lower frequency reception of radiation from earth stations and higher frequency for transmission to earth stations
• None of the above