I'm pretty sure it is true. (78% sure)
Answer:
D. Meters/Seconds
Explanation:
The time period of a wave is measured in seconds.
A typical wave involves both time and distance. Consider a sound wave, which is basically a periodic modulation of the local air pressure. We "hear" the sound because our ears respond to the variations of pressure.
The most common metric of a sound wave is frequency. This is the rate at which the change in pressure occurs, and is measured in cycles per second, formally known as "hertz". The period is the inverse of frequency andl has the units of seconds per cycle, commonly stated simply as seconds.
Answer:
Explanation:
Point beneath you forms a beautiful iridescent green
refractive index of Gasoline 
Wavelength of Green light is 
Here light first traverse from air(n=1) to gasoline , it reflects from front surface of gasoline(n=1.38) so it suffers a phase change. After this light reflect from rear surface of gasoline and there is a decrease in refractive index(n=1.38 to n=1.33), so there is no phase change occurs .
For constructive interference
here t= thickness of gasoline film
n=refractive index
for 
i sorry i thought of geocentric as something else it appears that the earth was the center
