im a bit confused on what the question is:(
if its just asking for the total number of km traveled it would be 21 km
C. It is answered by observation and evidence.
Good scientific explanations are defined, measurable and controllable. They can be answered by an experiment.
Since the Earth is almost spherical in shape, we are actually to find first the volume of the spherical segment at a depth of 1,000 m. The radius of the Earth is 6,371,000 meters. The volume of a spherical segment is:
V = 1/3*πh²(3r - h)
Substituting the values and making sure the units is in mm,
V = 1/3*π(1000 m * 1000 mm/1 m)²[3(6,371,000 m * 1000 mm/1 m) - (1000 m * 1000 mm/1 m)]
V = 2×10²² mm³
Thus, the total amount of bacteria is:
2×10²² mm³ * 100 bacteria/1 mm³ = 2×10²⁴ bacteria
The frequency of the radio station is

For radio waves (which are electromagnetic waves), the relationship between frequency f and wavelength

is

where c is the speed of light. Substituting the frequency of the radio station, we find the wavelength:

Frequency, f, is how many cycles of an oscillation occur per second and is measured in cycles per second or hertz (Hz). The period of a wave, T, is the amount of time it takes a wave to vibrate one full cycle. These two terms are inversely proportional to each other: f = 1/T and T = 1/f.

Hope It Helps!