Answer:
Step-by-step explanation:
This fact about the three insects shows that this insects have a common ancestor.
For the anatomical structure to be the same it means a structure or an individual who posses that anatomical structure is common to them which is the ancestor.
Although modifications has occurs, changes have abound that now give rise to different mouth structures there is still a common ground which is the anatomical structure produced by their ancestors and it is inherited and passed on to successive generations.