A Railroad Bridge Is Built Over a V-Shaped Canyon

Multiple Choice

A railroad bridge is built over a V-shaped canyon. If the supports are 8 feet long at each end, the center support is 560 feet long, and the supports increase in length by 4 feet with each support (from 8 feet to 560 feet) ,
What is the total length of all the supports?

A) 78,384 ft
B) 78,392 ft
C) 78,396 ft
D) 78,388 ft