c). Laertes is upset because Odysseus has just lied to him about his identity.
Explanation:
In Book XXIV of the epic poem "The Odyssey" by Homer, we find the character of Odysseus going to visit his old father and testing whether he remembered him or not. Choosing to be crafty with his father, he asked about himself and then told him tales of his encounter with Odysseus. When Leartes learned that he "Eperitus" had indeed met Odysseus but that has been five years since. On hearing this, Leartes got upset, cried and filled both of his hands with dust from the ground and put it over his own head. It was his way of mourning the loss of his son. This act of deception, Odysseus lying to his father made him upset.