Assertion (A):The bridge that was built over the railway

Assertion (A):
The bridge that was built over the railway track collapsed within a year of its construction.
Reason (R1):
The bridge had faulty design.
Reason (R2):
Kickbacks were paid by the contractor to the engineers.

1. If only reason 1 (R1) and not reason 2 (R2) is the reason for the assertion (A).
2. If only reason 2 (R2) and not reason 1 (R1) is the reason for the assertion (A).
3. If both (R1) and (R2) are reasons for the assertion (A).
4. If neither (R1) nor (R2) is the reason for the assertion (A).

Kickbacks do not imply use of faulty design or inferior quality material, which is the cause of collapse.