Using portfolio margin calculator for your retail broker, could you check the margin requirement for these three options? (a) if you were to sell 100 (1 lot) of SPY Dec31 175 p (b) if you were to sell 100 (1 lot) of SPY Jan 175p (c) if you were to sell 100 (1 lot) of SPY Jan 165p I will owe you a beer and a favor!
It seems like $20 for (b) if you were to sell 100 (1 lot) of SPY Jan 175p $6 for (c) if you were to sell 100 (1 lot) of SPY Jan 165p