How did the gross national product (gnp) of the united states change between 1940and 1944 it increased slightly it stayed the same it more than doubled it dropped significantly

It more than doubled.

Explanation:

Between  1940 and 1944, the Gross National Product of the United States of America expanded hugely, more than the twofold of the earlier years.  

The Gross National Product of a nation is characterized as the arrangement of definite merchandise and enterprises delivered by their generation factors and sold in the market amid a given period, generally one year.  

Amid the World War II, the Gross National Product increased as a result of the increase of industrial and productive activities, which were taken literally to the possible limit of production, so as to cover the costs of the war and give assets to the American powers battling in Europe and the Pacific.

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according to my calculation, the answer is d.