Continuous substitutability of capital and labour is shown by which of the following curves?

The point at which the total product curve begins to flatten out indicates:

Which of the following statements regarding the Cobb-Douglas Production Function Q = A Lα Kβ are correct? I. The positive constants α and β represent the output elasticities of labor and capital, respectively. II. Constant returns to scale are achieved when α + β = 1. III. The function can be expressed in logarithmic form as ln(Q) = ln(A) + α ln(L) + β ln(K). IV. The constant 'A' represents total factor productivity or technological progress. Choose the most appropriate answer from the options given below: