问题如下：
A refiner purcharsed April crude oil at $40 per barrel to produce gasoline and heating oil for sale in May. The 1-month future prices for gasoline and heating oil are $50/per barrel and 35 per barrel. The 5-3-2 crack spread is:
选项：
A.$4 per barrel.
B.$20 per barrel.
C.$140 per barrel.
D.$40 per barrel.
解释：
A is correct.
考点：crack spread
解析： 5-3-2 crack spread锁定的是购买5份crude oil生产3份gasoline、2份heating oil所产生的收益。因此5-3-2 crack spread=（3x $50）+ (2 x $35)- (5 x $40)= $20 for 5 barrels， 即$4 per barrel.
题目里面的已知条件不足
