A telephone is used for communication by humans over long distances.
Open water races of 5 to 25 kilometers are offered to long distance swimmers.
A telephone is used for communication by humans over 25 kilometers or more.
A telephone is used for communication by humans between what span?

[1] 25 kilometers or more
[2] members of their own species
[3] global ecosystems
[4] 5 centimeters
[5] 1 meter
[6] Males and females
[7] A set number of times
[8] 4 microns