Concept:Net National Product is measured after deducting depreciation, so adding back depreciation gives Gross National Product.Explanation:The formula is GNP=NNP+Depreciation Allowance.Given values: NNP=$50m and Depreciation =$10m.Substitute these values: GNP=$50m+$10m=$60m.Therefore, the Gross National Product of the country is $60m.Answer:B. $60m