Choosing where to park your emergency fund requires balancing yield, access, and safety. High-yield savings accounts at FDIC-insured banks have become popular because they offer substantially higher APYs than legacy checking accounts while keeping funds liquid and insured. Brokerage “sweep” or money market accounts may offer similar returns but can have different protections (SIPC vs FDIC) and sometimes variable access timing. Investments like index funds can produce higher long-term returns but carry market volatility and cannot be relied on for near-term cash needs. The principle for emergency funds is: prioritize immediate access and capital preservation over maximum return — you want the money when you need it, not to chase a little extra yield that might be temporarily lost in a downturn or delayed by settlement windows. This question tests that trade-off.