. What is the cost of carry for each of the following? Use only the following notations: r=the (domestic) risk-free rate; q=the dividend yield, u=the storage cost, y=the convenience yield, and r_f=the foreign risk-free rate. Assume that all are expressed with continuous compounding. (a) For a non-dividend-paying stock, it is _________ (b) For a stock index, it is _____________ (c) For a commodity with storage costs, it is _____________ (d) For a foreign currency, it is _____________