A portfolio contains two separate options: P1(K1) and C2(K2). The portfolio is short in P1(K1) and long in C2(K2). Assume that the two European options described above are for the same underlying assets and have the same maturity (T) and have no interim cash flows (i.e. no dividends). Assume that each of the options has a different strike (Ki) such that K1< K2 and that the strikes are equally spaced apart.