Explanation:

To find the correct one word substitution for the given group of words we need to check the meaning of the given options.

1. etymology - the study of the origin of words and the way in which their meanings have changed throughout history.

2. taxonomy - the branch of science concerned with classification, especially of organisms; systematics.

3. dermatology - the branch of medicine concerned with the diagnosis and treatment of skin disorders.

4. taxidermy - the art of preparing, stuffing, and mounting the skins of animals with lifelike effect.

After looking at the meaning of the given words it is clear that the correct substitution for the given group of words is 'taxidermy'. So option 4 is the correct answer.