Final answer:
Natural selection is a key mechanism of evolution that occurs when individuals with favorable traits are more likely to survive and reproduce.
Step-by-step explanation:
Natural selection is a key mechanism of evolution, and it occurs when individuals with favorable traits are more likely to survive and reproduce. The example that best illustrates a condition necessary for natural selection to occur is option c. Some bacteria have very specific temperature requirements. This is because natural selection requires selective pressure, such as a shortage of food, a predator, or a mating preference. In this case, bacteria that can thrive in specific temperature conditions will have an advantage and be more likely to survive and reproduce.