Answer:
A.
Explanation:
Because the trait undergoes a secondary loss; it has been there but it doesn't always appear in all generations.
<span>for accurate results, for example when they are making vaccines, these are weakened harmful or disease causing viruses,, too little of the virus then it would not be a vaccine or simply would not build you antibodies, and too much of it would not also not a vaccine since it will already inflict a disease or possibly be fatal</span>
Answer:
The answer is natural selection
Explanation:
The modern theory of evolution was developed by Charles Darwin, an amateur English naturalist, in the 19th century
The xylem cells or vessel!
