I think it is c but I’m not 100% sure so wait for someone else to answer too maybe ?
C) is definitely the bacterium!
A) look like a paramecium with it's flagela and vacuole
B) is a plant cell with chloroplasts
D) could be an animal cell, plant, or fungal since it has a nucleus
**remember: bacteria lack ALL membrane bound organelles: nucleus, mitochondria, chloroplasts, E.R.!!
Answer:
Doppler effect is a change in frequency and wavelength of a wave. It is caused by the change in distance between the thing creating the wave (causer) and whatever is measuring seeing or hearing the wave (watcher or observer). Another word for "causer" is "sender".
HOPE THIS HELPED!!!!!!!!!!!!!! XDDDD
Gas is the correct answer