An actual total loss is caused by:

1. (a) A total destruction of the subject matter of insurance.
2. (b) The loss of the subject matter by sinking, or by being broken up.
3. (c) Any damage to the subject matter which renders it valueless to the owner for the purposes for which he held it.
4. (d) Any other event which entirely deprives the owner of the possession, at the port of destination, of the subject matter.