Figure $15\mathrm{.}36$ shows the Solver Sensitivity Report for the student investment scenario from Problems $7$ and $14$ from Chapter $13.$ Using only the information in the Sensitivity Report, answer the following ques$-$tions, explaining what information you used in the Sensitivity Report.

a$.$ How much would the return on stock B have to be in order for the optimal solution to invest fully in that stock?

b$.$ How much would the return on stock C have to increase in order to invest fully in that stock?

c$.$ Explain the value of the shadow price for the total investment constraint. If the student could borrow $$1,000$ at $8\%$ a year to increase her total investment, what would you recommend and why?