Answer:
C. At a particular instant
Explanation:
Speed is the defined as the ratio between the distance covered by an object and the time taken:

where d is the distance and t the time.
However, there are two possible measurements of speed:
- Average speed: this is the speed measured over a non-zero time interval (for example: a car moving 100 metres in 5 seconds; its average speed is

- Instantaneous speed: this is the speed of an object measured at a particular instant in time, so for a time interval that tends to zero. So, in the previous example, the average speed is 20 m/s but the instantaneous speed of the car at various instants of time can be different from that value.
Plastic is what they are made of
Speed is v = d/t
Or speed is distance over time
So...
40min / 60min = 0.6667 or 2/3 --> Finding what proportion 40 minutes is to an hour or 60 minutes as we need the units of hours to match up
45km/h = d/0.6667h
d = (45)(0.667)
d = 30.0015 or 30km