One type of density change is mass over volume.
A. Natural Selection. This is because the weeds that are not resistant to it die out before they can reproduce, but the resistant ones grow to maturity and then reproduce, passing down the resistance gene. Over time, the resistance gene would become a normal thing in weeds, while the non-resistant gene would not exist anyone, since the gene could not be passed on.
The immune system is the bodies defense against invaders and is located in all body tissues with concentration in the mucosal surfaces and skin.
Answer:
I believe the answer is B
Explanation:
Undisturbed rock formations on mountain tops are basically an indication of the Earth's age. This can be supported by the law of proposition. This law states that the youngest sediments or rock are found at the top of the sequence and the oldest are found at the bottom - given they're undisturbed. So the higher mountain tops or rocks formation are, the more we can say that the Earth is indeed very old.
