In a binomial option pricing model, when moving from valuing an option on a non-dividend paying stock to an index option which of the following is true for estimating uptick probability P?

		The risk-free rate is replaced by the excess of the domestic risk-free rate over the foreign risk-free rate in all calculations.
		The formula for u changes.
		The risk-free rate is replaced by the excess of the domestic risk-free rate over the dividend yield for discounting.
		The risk-free rate be replaced by the excess of the foreign risk-free rate over the domestic risk-free rate when p is calculated.