A benchmark index's performance last year was $8\%$ with a volatility of $6\%.$ What fund is most likely being managed by a closet indexer?

Fund B: Return $7\mathrm{.}8\%$; Volatility $6\mathrm{.}4\%$

Fund D: Return $10\mathrm{.}3\%$; Volatility $6\%$

Fund A: Return $8\mathrm{.}2\%$; Volatility $11\%$

Fund C: Return $8\mathrm{.}1\%$; Volatility $20\%$