The correct answer is: Both A & B.
Special reports are necessary when the sum insured is high or when the age of the insured is advanced. This is because these factors increase the risk of the insurer and they need to be sure that the insured is able to pay the premiums.
When the sum insured is high, the insurer needs to be sure that the insured has the financial means to pay the claim if it is made. If the insured is advanced in age, they are more likely to make a claim and the insurer needs to be sure that they will be able to pay the claim.
Special reports can include a medical exam, a financial statement, or other information that the insurer needs to assess the risk.