From a financial cash-flow perspective, and assuming everything else held constant, which of the following changes to a firm's balance sheet would be a "good" thing, and why?

a. A firm increasing assets, because doing so ties up cash flow.

b. A firm decreasing assets, because doing so ties up cash flow.

c. A firm increasing liabilities, because doing so frees up cash flow.

d. A firm decreasing liabilities, because doing so frees up cash flow.