Answer:
age and knowledge
Step-by-step explanation:
A speaker could have difficulty presenting to a child audience because of the difference in age and knowledge between the speaker and this audience. This is because the speaker should adapt his speech with concepts and words appropriate to the age and knowledge of the children. This is a big challenge, as the speaker, being an adult, has a higher mindset and vocabulary than children, and moreover, this speaker may not understand subjects that would be interesting and understandable to children.