Answer:
A.
Explanation:
Because the trait undergoes a secondary loss; it has been there but it doesn't always appear in all generations.
It is called a watershed.
Lying generally between the foot of acontinental rise and a mid-ocean ridge,abyssal plains cover more than 50% of the Earth's surface. the zone of theocean floor that separates the thinoceanic crust from thick continentalcrust. ... the slope between the outer edge of the continental shelf and thedeep ocean floor.
DNA is the answer (if you could put me brainliest that would be great)
