You, East, hold at IMP scoring:
♠J1043 ♥82 ♦A964 ♣KJ2
On this, your very first board with a new partner, you have a chance to use a convention.
At favourable vulnerability, you respond 3♣ to partner's opening bid of 1♠ (five-card majors, 15-17 no trump, almost all 5-3-3-2 shapes in range open 1NT). Thereby, you show 7-10 hcp and four spades; you imply but do not promise a relatively balanced hand.
South bids 4♥ and West passes slowly. Notwithstanding whether or not you would in any circumstances do anything other than pass with the actual hand, please answer the following question.
After North's pass, which of these best describes the ethical constraints upon you?
Benefits include:
Plus... it's free!