I am confused on this question.

2) a. Using diagrams as aids, explain the changes in the optimal investment schedule for: 1 . A decrease in :' 11. A decrease in =. b. Using the optimal investment schedule diagram, explain the effects of a decrease in / on the optimal investment schedule and investment demand. c. Derive the optimal investment rule for the firm under the following assumptions: The depreciation rate is 0.5 11. The MC of investment is 1 consumption unit. 111. Any capital remaining at the end of the second period can be sold at a price of 2 consumption units