sentences:  In the case of put options, the trader will buy some number of options having striking price A, but write (sell) a larger number of options having striking price B, where B is less than A.The "straight" ratio-spread describes this strategy if the trader buys and writes (sells) options having the same expiration.If, instead, the trader executes this strategy by buying options having expiration in one month but writing (selling) options having expiration in a different month, this is known as a ratio-diagonal trade.