While taking a practice ACT test, I came across a confusing grammar problem. The sentences given in the passage are as follows:
"Many people believe that language is the domain of human beings. However, cats have developed an intricate language not for each other, but for the human beings who have adopted them as pets."
The bolded text would best be replaced by:
- NO CHANGE
- developed, an intricate language
- developed an intricate language,
- developed; an intricate language
The answer is very obviously not 2 or 4. The supposedly correct answer is 1. NO CHANGE, but I do not understand why answer 3 is not correct. A pair of commas is used to set aside information that adds to the sentence, but is not necessary for the sentence to be understood.
The book where I came across this problem states that there is no need for a pause, thus making answer choice 1 the correct answer. Why, then, do I feel like the sentence flows better with a comma before "not"?