Here's a problem to solve: Based on the Doppler effect, the electromagnetic waves reaching Earth from a galaxy that is moving away from Earth would be expected to

Among the 4 following options, which is the correct answer?

- A: experience an increase in their amplitude.
 
- B: experience an increase in frequency.
 
- C: experience a decrease from transverse waves to longitudinal waves.
 
- D: experience a decrease in frequency.
 