Answer:
Option c) Diaphragm and external intercostals only
Step-by-step explanation:
This can be explained as when the air is inspired by us there is contraction in the muscles of external intercostals and diaphragm. This leads to a decrease in pressure and an increase in volume which allows the inpiration of air easily.
Therefore, it can be concluded that neither the diaphragm alone nor the diaphragm along with the internal intercostals can allow to inspire air but only the diaphragm along with external intercostals can allow inspiration of ai.r