Step 1: Pick out the exact reason given in the case.
The finance manager suggested raising funds through equity because the market was bullish.
Step 2: Recall the factors that affect a financing decision.
These include cost of the source, risk involved, cash flow position of the company, and the state of the capital market, that is, whether it is bullish or bearish.
Step 3: Connect the bullish market to the choice of equity.
In a bullish market investors are optimistic and share prices are generally high, so it becomes a good time for a company to sell new shares at a favourable price with less effort.
Step 4: Rule out the other options.
Cash flow position is about the ability to service fixed payments, flexibility is about ease of changing the capital structure later, and cost of debt has nothing to do with equity at all, so none of these match the reasoning in the case.
Final answer: Option 4, Stock market conditions.