In a population where most of the individuals have long, narrow noses, a child is born with a short, broad nose. What's the most likely evolutionary explanation for this variation?

A) Both parents of this child are from another population.
B) Humidity in the area is increasing, and selection pressure is changing.
C) The child reflects the normal variation around the average type.
D) A mutation must have occurred to produce a new allele of the nose shape gene.