Consider a tuna stock at the beginning of time t, denoted by the variable Xt, measured in metric tons. Suppose that in each period, the stock of tuna grows according to the difference equation X4+1 = X+ + F(X+) – Ht, where F(X+) is a function representing the net growth of tuna and H+ is the harvest of tuna at time t. Suppose that net growth of tuna depends on the size of the fish stock and is given by the function F(X+) = X+(1 – Xt). 1.A. (0.5 points] Explain the concept of a steady state. What are the biological steady states for the tuna stock if there is no harvesting? Are these steady states stable? 1.B. [0.5 points] Is there some level of X at which the net growth of tuna is maximized? If so, what is it? 1.C. [0.5 points] Now suppose that we have the following simple rule for determining the harvest of tuna: H+ = aXt. Determine the steady state stock and harvest levels of tuna. (Note: Actually, there are two steady states, one when X = 0. I'm only interested in the second one.)