Question

Assertion
The bridges were declared unsafe after a long use.
Reason
Elastic strength of bridges losses with time.
A. If both assertion and reason are true and reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion and reason are both false.

Answer 1

One could think of bridges and their construction. Then you could think of the possibilities that could result in the collapse of these bridges. Then think of the duration that the bridges could be considered safe. Thereby you could relate the assertion and reason and hence find the answer.

Complete step-by-step solution:
Everyday, every bridge tolerates alternating strains for multiple times for long durations. When these bridges are used for very long duration, its strength is being lost as a result of which the amount of strain corresponding to a particular amount of stress is becoming very high and finally leads to the collapse of this bridge. Hence, we could conclude that the elastic strength of the bridge is lost over time and thus the bridges are declared unsafe after a long use.
Hence, option A is found to be true.

Note: Bridge designers could be called force balancers. They balance two forces that are: compression and tension. One should be aware that, the longer the bridge is, the heavier it will be and so will be the risk of its collapse. So, the designers as well as engineers should be very careful while carrying out the task of construction of a bridge.