Each sentence below has two blanks, each blank indicating that something has been omitted. Choose the set of words for each blank that best fits the meaning of the sentence as a whole.
If there is nothing to absorb the energy of sound waves, they travel on ........... , but their intensity ........... as they travel further from their source

Options

A. everlasting, decreases
B. always, improves
C. forever, inclines
D. steadily, deflates