Respuesta :

speed (or velocity) = distance / time

distance (or displacement) = 30.0 – 10.0
= 20.0 m

time = 160.0 – 80.0 = 80.0 s

average velocity = 20.0 / 80.0 = 0.25 m/s

but because the line has a negative gradient the answer is -0.25 m/s which is B