Assume that investors want to invest in the most efficient (aka optimal) portfolios. The existence of a risk-less security in the risk & return trade-off:

		does not influence investors preferences regarding which risky portfolio to hold.
		Results in investors all holding different portfolios of risky assets depending on their individual risk preferences
		Results in investors all holding the same portfolio of risky assets which corresponds to the tangency point of the efficient portfolio frontier of risky assets and a line through the risk-less asset's return.
		None of the alternative responses are accurate.