【Analysis】From the table, we can see that the arrangement follows the pattern of an isosceles triangle with the top vertex at the upper left corner. Each diagonal group of numbers has a count of $1,2,3,4,5 \cdots$. Therefore, the first column of the 10th row should be on the 14th diagonal row. To find the last number of the 14th diagonal row and then subtract 4. Solve accordingly.

【Solution】Solution: According to the above analysis, the last number of the 14th diagonal row is:
$$
\begin{array}{l}
1+2+3+\cdots+14 \\
=(14+1)+(13+2)+\cdots+(8+7) \\
=15 \times 7 \\
=105 \\
105-4=101
\end{array}
$$

Therefore, the answer is: $D$.
5. (10 points) Arrange natural numbers in the method shown in the figure. The number in the 10th row and 5th column is $(）$
A. 79
B. 87
C. 94
D. 101