Expansion is the correct answer
The easiest way to remember is Superlative or “super” is the best, right? Therefore, superlative is -est, like best, largest, greatest. Comparative is the -er. Therefore, that is more, larger, or greater. The answer, then, is B, as C simply and adjective this is neither comparative nor superlative.
To sound more sophisticated it could be written as: Hello, Cory
To add punctuation it would be simply: Hi, Cory
Or if casually like if you were texting it could be: Hi Core- left the same.
