Answer: possibly A
Explanation: B an C are not it because they are more like mutations. D humans don’t always become immune.
<span>Any physical or psychological event that produces stress</span>
Answer:
The process by which plants make food through sunlight is called photosynthesis...
<span>chordates are the animals which are in phylum chordata and have backbone
</span>The trait that is ancestral to all chordates is <span>a vertebral column that is backbone
so option D is correct
hope it helps</span>
