I think, materials collided due to strong gravitational forces..
Plates at our planet's surface move because of the intense heat in the earth's core that causes molten rock in the mantel layer to move.It moves in a pattern called a convection cell forms when warm material rises,cools,and eventually sink down.
The answer to this question would be: rapid impulse transmission.
By having organ near the head, the brain can process the information faster because the length of the nerve that carries the impulse from organ would be much shorter. The nerve also at lower risk of damage since it was shorter.
But it makes the head very important and damage to the head can cause much more problem than any part of the body.
Answer: The correct answer is -
D) giraffes having increasingly longer necks over time.
Natural selection is an evolutionary mechanism that was proposed by Darwin.
According to this mechanism, organisms that are better capable of adapting to their changing environmental conditions, survive and increase their number through reproduction whereas other are eliminated from the population.
Example - Long neck of Giraffe, which is much elongated, lofty stature, that was beautifully adapted for browsing on the higher tree branches. This was an adaptation with slow and gradual change in the gene frequency as the lower vegetation was eaten by other animals. Due to this, giraffes had to search for other source (that was higher tree branches).
This is considered as a peculiar example of natural selection.
Cellular respiration occurs in both eukaryotic and prokaryotic cells, with most reactions taking place in the cytoplasm of prokaryotes and in the mitochondria of eukaryotes.
Hope it Helps!