Final answer:
The healthiest coping behavior exhibited by the parents is (d) throwing flowers on the lake in the memory of their child, suggesting acknowledgment and remembrance in a constructive way.
Step-by-step explanation:
Throwing flowers into the lake on each anniversary of the disaster is a sign that the parents are coping well with their loss. This conduct points to a memorial and memory method that permits a healthy and ongoing awareness of their child's life and loss.
It signifies that they have found a way to express their grief and keep the memory of their child alive, without preventing their surviving children from living their lives or making their lost child a constant, unchanged presence in their daily lives.