3. A “late onset illness” is—
(a)a malignancy, or other physical disorder which is capable of being caused by an occupational exposure occurring 7 or more years before the onset of the illness or the date of death as the case may be;
(b)a mental disorder which is capable of being caused by an incident occurring 7 or more years before the onset of the illness; or
(c)a mental disorder capable of being caused by an incident occurring less than 7 years before the date of onset of the illness, which disorder is capable of causing the person suffering from it to be unable to seek medical help for the disorder within 7 years of the date of onset of the illness.