The function a represents the cost of manufacturing product A, in hundreds of dollars, and the function b represents the cost of manufacturing product B, in hundreds of dollars. a(t)=5t+2b(t)=7t2-2t+4Find the expression that describes the total cost of manufacturing both products, a(t) + b(t).A. 7t2 + 7t - 6B. 7t2 - 3t + 6C. 7t2 - 7t + 2D. 7t2 + 3t + 6