Answer:
Your answer is probably A). If you find a fossil of an armored fish in layer A, and you find a fossil of a trilobite in layer B (five layers deeper), then you can safely assume that the trilobite is older than the armored fish.
Answer:
Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.
Answer
Environmental pressures
Basically every animal adapts to pressures from their environment in different ways, causing them to have different shapes and sizes