A covered credit spread call consists of which of the following positions? A long position in the underlying asset and: A. short in a credit spread put. B. short in a credit spread call. C. the purchase of a credit spread put, and the sale of a credit spread call. D. short an at-the-money call and put at the same strike.  
这题，选a不对么？
y上升的话，p下降，spread上升，call上升，put下降，所以应该short put啊