Kindly assist with the answer.

Question 4 [10] X, Y and Z were stranded on a small island in the middle of the ocean after their cruise ship sank. Although there is fresh water on the island, there is absolutely nothing to eat. In order to stay alive, X and Y decide to eat Z, who was already very weak. X and Y were later rescued, but Z's dependants institute a claim for loss of support. You are X and Y's advocate. Discuss the defence you would raise to exclude wrongfulness and refer to applicable case law