Answer: A.
Explanation:
The author was disappointed when he/she learned that only adults are able to participate (a rule) in the art contest.
Ubiquitous means that the subject is everywhere or pervasive.
Confusing means bewildering or perplexing.
So if something is ubiquitous, the reason for it being so might not be clearly understood
Answer:
We can learn what animals contribute to our sociality and what animals we need to worry about
Explanation:
like bees and butterflies pollinate our flowers but like mosquitoes infect us with viruses
