Goods added to inventories during a given year are:

a) counted as part of GDP for that year even thought they do not pass through markets

b) not counted as part of GDP for that year because they do not pass through markets

c) not counted as part of GDP for that year because that would amount to double-counting, once the year they are produced and again the year they are sold

d) arbitrarily valued at half the cost of production in calculating GDP for that year, since there is always a chance they will never be sold