Ateam of engineers has designed a new anti-collision device for cars. the device is intended to reduce the chance of collisions between cars. the engineers have decided to test the device on model cars in laboratory conditions before testing it on real cars.

which test would be most useful to decide if the device works as intended?
a) comparing the frequency of collisions with and without the device
b) measuring the amount of damage after a collision, with the device fitted
c) observing how the number of collisions varies with the speed of the cars
d) comparing the performance of the device with that of other similar devices

As the device is intended to reduce the chance of collision between cars, the test used has to address this issue hence the answer is A. B tests the amount of damage which is not what the device is intended to do. C addresses the device functionality with respect to the speed of the car which is irrelevant as the device should reduce chance of collision irregardless of the car's speed. D would be useful to test the device although it will not be the most useful to test if the device works as intended, this would probably be used in a later stage of testing to determine the performance and consistency of the device, for example.

ok so u have2 basically