Answer:
A) $24 billion
Explanation:
Here is the complete question : 
 Potential Real GDP $200 Billion 
Natural Rate of Unemployment- 6 Percent 
Actual Rate of Unemployment- 12 Percent 
Refer to the accompanying data, which is for a specific year in a hypothetical economy for which Okun's law is applicable. The amount of output being forgone by the economy is
 C) $15 billion. D) $18 billion. A) $12 billion. B) $24 billion. 
According to Okun's law, a 1% decline in unemployment results in a 2% fall in potential GDP 
Decline in unemployment = Actual Rate of Unemployment - Natural Rate of Unemployment
12 - 6 = 6%
decline in output = 6% x 2% = 12%
potential GDP lost = 12% x $200 Billion  = 24 billion