Which of the following statements stands true with respect to conserving fossil fuels ?
a)once burnt are gone
b)there is hardly any economical method to make synthetic fuels from coal
c)oil recovery processes lead to losses as it still leaves behind oil trapped in the rocks
d)all of the above are true



I say d) all of the above 
is the correct answer
i am sure
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The answer is all the above r correct option is d
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