问一个level1的问题，搞糊涂了 option, required, decrease

zaz007y

08note book5 120页 Z-spread-OAS=option cost in precent

OAS<Z-spread is call option bond

然后161练习第10题答案却说

OAS is less than Z-spread, the effect of the embedded option is to decrease the required yield, so it must be a put option and not a call option

这到底是什么意思？