The correct answer is: B. When sum insured is very large.
An underwriter is a person who assesses the risk of an insurance policy and decides whether to offer it and at what price. When the sum insured is very large, the underwriter has to be very careful because the potential loss is also very large. The underwriter will need to carefully assess the risk and make sure that the premium is high enough to cover the potential loss.
The other options are incorrect because they do not pose as much risk to the underwriter. When the sum insured is very small, the potential loss is also very small. When income is very small, the underwriter may be more likely to offer a policy because the potential loss is also small. When income is very high, the underwriter may be more likely to offer a policy because the insured person is likely to be able to afford the premium.