Which statement about diffraction is correct? A. Sound waves bend around the corners of various obstacles.
B. Sound waves can only travel in straight lines.
C. The amplitudes of two waves combine to appear as a wave smaller than the individual waves.
D. The amplitudes of two waves combine to appear as one big wave.

The best answer is (a) which is universal law is in effect at all times. it is constantly at play in everything we do and governs our lives. it is also important to note that universal law applies to not only everything on earth, but everything in the universe as well, which is another reason why it is in effect at all times.

Iwould think it is temperature, silica, oxides (gases)

Assuming you're referring to significant figures, none of these answer choices are shown to be zero as significant digits. did you, by chance, forget to add something?