A firm has three investment opportunities:

Time: $0123$

Cash Flow

Project A $-3002045$

Project B $-100606060$

Project C $-6056560$

The firm has $$100$ in retained earnings to invest, but the firm is capital constrained and cannot

borrow any additional funds this year. Note that the firm cannot complete part of a project, and

it cannot pursue any project more than once, but it could pursue multiple projects. Due to the

different levels of risk, each of the two projects has a different cost of capital: the cost of capital

for projects A$,$ B$,$ and C are $5\%,6\%,$ and $7\%$ respectively. What should the firm do$?$ Explain.