The answer is C.
She wouldn't wave to her her sister if she felt betrayed
She wouldn't really wave "low key" if she were feeling impatient
If she were unaware she wouldn't even notice her
Annabeth's actions in Chapter 18, when she distracts Cerberus with the red ball she stole, prove that she is intelligent and quick on her feet, always preparing. These are all traits of a daughter of the goddess Athena.
The answer is, 'his silence when Antinous confronts Odysseus'.
