Snowball and Napoleon were the most intelligent and active of all the animals at the farm. The fact that they even argued about those suggestions they seemed to agree with, clearly shows that there was an underlying fight for power between them. There was a need to show that they were somehow not part of the same mind, by means of opposing to whatever the other one suggested.
A is used for words that begin with a consonant sound;
an is used for words that begin with a vowel sound:
What a/an exciting summer it has been for Jalia.
"exciting" is the word right after a/an, and it starts with a vowel sound (short vowel e) and is a vowel.
The answer is an => What an exciting summer it has been for Jalia.
Explanation:
what is the rest of the sentence?