All of these are necessary, but what you need the most I would say is
D. Movement
Without movement, your body can stiff up, causing muscle problems which can lead to many various things.
Answer:
B). Both are endotherms
Explanation:
Both birds and mammals are warm-blooded, which is the meaning of endotherm.
Hope this helps!
~PurpleMist
Did you try looking it up online, they give good interpretations
1. Ecosystems have D. Biotic and abiotic parts.
2. Another name for food level is A. Tropic level.