2. It is known that the distance between Xiao Wang's and Xiao Li's homes is $16 \mathrm{~km}$. Xiao Wang rides a bicycle from home at a uniform linear speed of $12 \mathrm{~km} / \mathrm{h}$, and Xiao Li rides an electric bike from home at the same time at a uniform linear speed of $24 \mathrm{~km} / \mathrm{h}$. After $20 \mathrm{~min}$, Xiao Wang arrives at location $M$, and Xiao Li arrives at location $N$. Let the distance between $M$ and $N$ be $d \mathrm{~km}$. Then the value of $d$ is ( ).
(A) 4
(B) 20
(C) $4,12,20,28$
(D) $[4,28]$
2.D.

After moving for $20 \mathrm{~min}$, Xiao Wang walked $4 \mathrm{~km}$, and Xiao Li walked $8 \mathrm{~km}$. Location $M$ is on the circle "with Xiao Wang's home as the center and a radius of $4 \mathrm{~km}$", and location $N$ is on the circle "with Xiao Li's home as the center and a radius of $8 \mathrm{~km}$", as shown in Figure 2. The closest distance between the two circles is $16-4-8=4 \mathrm{~km}$, and the farthest distance between the two circles is
$$
16+4+8=28 \mathrm{~km} \text {.  }
$$

In general, the value of $d$ is
$4 \leqslant d \leqslant 28$.