Hello there!
Your answer would be D). More than 5%
The reason why your answer would be "More than 5%" is because the Average rate of return on stocks is roughly about 7% overall. The term "rate of return" pretty much means the money that you would be getting back, or "profit" in a investment. Would you see the numbers for rate of return mostly in the stock market, business, and other types of investments someone makes. The words "Over time" is probably talking about the times all the way back to the 1950s where the returns were high, to this generation, which had a negative decrease in % of rate of return. That's why the question is asking you what the rate over time is, not just a specific time period.