Question

Identify the level of use of the following sentence. She's never looked so cool. formal

Answer 1

The correct answer should be informal.
Informal level of language involves the use of slang words, and cool is a slang word, so this sentence cannot be formal by any means. It is also not general due to a slang word being used. Substandard language would mean that it is not grammatically correct, and this sentence is, so this is also incorrect.