You can
put this solution on YOUR website!B and C are definitely non-linear.
A can be linear.
d = rt
The distance is directly related to the speed and to the time.
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In t = d/r, t is inversely related to r (rate or speed). If it's graphed with axes of r and t, it's a hyperbola, not a straight line --> not linear.
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If the speed is constant, then the relation between time and distance is linear.
It's tricky.