Respuesta :
He's increased his powers of scientific observation. His observation is empirical evidence. Empiricism relies on observation and experimentation.
The correct answer is A) he has made observations of the natural world.
When Justin notices that a particular type of Caterpillar feeds only on Cottonwood trees in his neighborhood, he has made observations of the natural world. So he is using the scientific method for research. Observation is an important component in researching because it allows you to understand the phenomena in the study.
The other options of the question were, b) he has used technology, c) he has performed a practical experiment, and d) he has performed an unethical experiment.