Final answer:
The loss of goods sunk at sea is not covered by the insurance policy because the policy was purchased after the goods had already been lost, which is a condition not generally covered by insurance.
Step-by-step explanation:
The scenario presented indicates that the coverage was purchased after the loss of the goods had already occurred. Insurance policies typically cover losses that happen after the policy has gone into effect. Given that the clients bought the insurance to protect their interest in the shipment after it had already sunk at sea, this loss would not be covered. This event occurred before the insurance policy was in place, making any claims for this particular incident invalid.