Recall the Application About the Price of Wolfram During World

Recall the Application about the price of wolfram during World War II to answer the following question(s) .
-Recall the Application. Wolfram is an ore of tungsten from neutral Spain required for making armor plate and armor-piercing shell., When the World War II Allies, the United States, the UK and others, tried to buy up all of production to deny tungsten to the Axis, Germany and Italy, the program became very expensive because:

A) mining was more expensive during the war.
B) war makes variable costs higher due to the greater security precautions needed.
C) Spanish firms increased quantity supplied dramatically in response to price rising dramatically.
D) all of the above