The purpose of this exercise is to argue that when a forward contract for a share of stock is negotiated between two (distinct) individuals, the hypothesis of no arbitrage determines the strike price uniquely. More precisely, suppose two individuals A (holder) and B (writer) negotiate a forward contract at time 0 for a share of stock with expiration date T > 0 and strike price X. As before, let S_t denote the price of the stock at time t and let r be the (constant) interest rate, with continuous compounding. Show that under the hypothesis of no arbitrage, we must have: X = S_0 e^rT