It is impossible to her to see the answer because there is too much of her data and it can't be calculated in appropriate way. If she lowers her data, then she can see her answer where she entered it in the cell.
She must know how much data is too much data so she could know how much of it she can enter successfully to the cell. The answer c) can also be right but it depends of how much data did she enter.
D) cannot be correct because the computer will never show if there is a mistake in the formula and answer A) cannot be correct to because it don't depend on cell wide.
The author is writing the passage to talk about Conrad's life as a black man in Nigeria and the way he feels about the other black people's lives in Nigeria too.
