ASAP! GIVING BRAINLIEST! Please read the question THEN answer CORRECTLY! NO guessing. I say no guessing because people usually guess on my questions.

Answer:
A. A man of disreputable nature.
Explanation:
Just by looking at the question and answers, you can determine that the most formal statement is A. A man of disreputable nature. By the use of the word formal, people tend to think of respectful/professional words/things. The words shady character and snake in the grass are more of a casual/informal way of describing a "suspicious" person.