C is the answer. Hope this helps
The answer is interval.
Each weight is increasing at an interval of 5 lbs with each child
Parallel lines are lines that has same slope but different y intercept
Perpendicular line has a slopes that are opposite sign and oppose numbers and if you plot them you will find the intersection tent intercept could be the same or different
Example
Y= -1/2+8
Y=2/1+5
A:B:C = 2:4:4
A = 210km
So B & C = 210*2 = 420km
Total distance = 210 + 420 + 420
= 1050km