In the context of investment performance evaluation, selecting an appropriate benchmark is critical for assessing the relative performance of a portfolio. Consider a large-cap U.S. equity fund that primarily invests in companies included in the S&P 500 index. When benchmarking the performance of this fund, the selection should reflect the investment style and the asset class of the fund. Which of the following benchmarks would be most suitable for evaluating the performance of this large-cap U.S. equity fund?