<span>undergo a dramatic decline in size, possibly to a stable level at or below 1,800 individuals.</span>
Answer:
the answer is D ecosystem
Therefore, in Doppler Effect only the frequency and wavelength are changes and the wave speed does not change
Answer: B. Water breaks down into oxygen molecules for respiration.
Water is the required for photosynthesis, a process by which plants (terrestrial and aquatic) makes their food by utilizing water as a reactant to produce oxygen and glucose as product. The glucose act as a source of energy for conducting various metabolic processes in plants but oxygen is released in the air.

This oxygen is necessary for terrestrial and aquatic animals for respiration. Therefore, water breaks down into oxygen by the process of photosynthesis, hence water plays important role in respiration in living beings.