Number 1) is incorrect. No one says it.
2) implies that you do not have first hand knowledge of something, but know about it. It implies distance. For instance, "I am aware that my cousin got married last year, but I didn't attend the wedding." It is also commonly used as a reply. For example, if I say that you don't know that your cousin got married, you might say that you are aware of it.
3) is the most commonly used. It just means to know. "I know you are tired." "Do you know where we're going?" "He knows my secret."