T. [25 points) Let 5' he the value of a stock following the usual process d3 = det + eSdz where dz is a WiEIIEI' process. Let H be a portfolio consisting of one unit of shorted derivative whose value is f, and an amount A of stock. {a} (It!I points} Dene. in terms of all], what it means for H to he in stantaneously risk free and derive, using Ito's Lemma, the correct choice of A for this to hold at an},r given time t. In the process of doing thisI give an explicit formula for rill if this choice is made. {h} {5 points} What should he the instantaneous return % of [I he if H is instantaneously riskfree? Justify your answer. {c} {IllI points) Use the previous two parts to derive the ElackScholes differential equation