a) Fire
b) Failure by excessive deformation
c) Corrosion
d) Repairable damage or crack due to fatigue

Answer: b
Explanation: Limit state of strength are prescribed to avoid collapse of structure which may endanger safety of life and property. It includes (i) loss of equilibrium of whole or part of structure, (ii) loss of stability of structure as a whole or part of structure, (iii) failure by excessive deformation, (iv) fracture due to fatigue , (v) brittle fracture.