Question

Which of the following is not an example of evolution?

		a. A farmer allows only short-haired sheep to reproduce, and subsequent generations of sheep have shorter and shorter hair.
		b. A female crab mates with a large-clawed male instead of a small-clawed male, and 80% of her sons have large claws.
		c. A parasite kills half of the crops in a field. At the end of the season the farmer collects the seeds. The next season the same parasite kills only 25% of the crops planted from these seeds.
		d. A population of plants grown in nutrient-rich soil is 4.5 cm taller on average than an adjacent population grown in nutrient-poor soil.