Which of the Following Is an Example of a Scientific

Which of the following is an example of a scientific hypothesis?

A) 'Space exploration benefits our world and Australia needs to increase funding it's space program.
B) 'Marital satisfaction tends to improve when the youngest child is grown and leaves the home because parents now have more time and energy for the marital relationship.'
C) 'HIV causes AIDS, and AIDS is a disease and will never be cured.'
D) 'If a tree falls in the forest, and no one is there to hear it; does it make a sound?'