2008-II-17

答案：C
$\begin{array}{cl}
& 0.049~876~5 \\
= & 0.05 \text{(準確至二位小數)} \\
& 0.049~876~5 \\
= & 0.049~9 \text{(準確至三位有效數字)} \\
& 0.049~876~5 \\
= & 0.049~9 \text{(準確至四位小數)} \\
& 0.049~876~5 \\
= & 0.049~877 \text{(準確至五位有位數字)}
\end{array}$