Carbon dioxide is the compound in photosynthesis, I'm pretty sure
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.
<span>The complete statement is this: 'An increase in food and a decrease in predators would most likely increase genetic variation in a population. An increase in available food is an environmental factor which brings about genetic variation in the population of a specie.</span><span />
Chow chows are so adorable!!!