d) d = 2.5t, continuous
Step-by-step explanation:
Jeff is traveling at the same pace, so he is moving at constant speed: its motion is a uniform motion, so the distance he covers (d) as a function of the time (t) is expressed by the law
(1)
where v is Jeff's speed.
We can find the speed from the initial data:
t = 2 hours
d = 5 miles
so, the speed is given by the ratio between the distance and the time

Therefore, equation (1) becomes
and the graph is continuous, because t can have any real value.