Select the correct answer.


A charity's outreach program is working to provide food and medicine to the people affected by a hurricane. The members drive in a truck from their headquarters at A, as shown in the image, to the locations B, C, D, E, F, G, and H and then go back to their office. What is the total length of their drive?

A.
20 units
B.
30 units
C.
40 units
D.
50 units