Question

which of the following resulted from a genetic variation that was favored by natural selection? a. the small size of a chihuahua b. cancer in a lab rat c. the long neck of a giraffe d. smoothness of a river rock

Explanation:

• Option A: Chihuahua's small size is due to artificial selection (human - directed breeding), not natural selection.
• Option B: Cancer in a lab rat is a disease, not a trait resulting from natural selection - favored genetic variation.
• Option C: Giraffes with longer necks had an advantage in reaching food (leaves on tall trees) in their environment. Over time, this genetic variation (for longer necks) was favored by natural selection as it increased their survival and reproductive success.
• Option D: The smoothness of a river rock is a result of physical processes like erosion (water - related abrasion), not genetic variation and natural selection.

Answer:

C. the long neck of a giraffe