An economy has the production function

Y = K + (K+L)²

whereY= output,K= capital, andL= labor. This production function has:

A. Constant returns to scale and a diminishing marginal product of capital

B. Constant returns to scale and a constant marginal product of capital

C. Decreasing returns to scale and a diminishing marginal product of capital

D. Increasing returns to scale and a diminishing marginal product of capital

E. Constant returns to scale and an increasing marginal product of capital

F. None of the above