Could you please explain every option and how to solve this type of question in detail? Thanks a lot.

Consider an apple juice company whose marginal product of labor and marginal product of capital are respectively given by MPL (L, K) = K and MPK (L, K) = VK for any input choice where L and K are the total labor and capital employed. The current input prices are w= 10 and r= 20, respectively. Suppose that the company currently hires (L, K) = (200,100) to produce 2000 units of output. Which of the following statements is true? d The firm could lower its production cost by substituting a part of its current labor employment with capital. ver The firm has minimized its production cost at (L. K) = (200, 100). The marginal rate of technical substitution is (approximately) 1 at (L.K) = (200.100). The firm could lower its production cost by substituting a part of its current capital employment with labor