21. In a railway track, two rails are joined end to end with a gap in between them because A.Steel can be saved B.Accidents due to contraction in winter can be avoided C.Air-gaps are necessary for bearing the weight of running train D.Accidents due to expansion in summer can be avoided
Option D Solution: In a railway track, two rails are joined end to end with a gap in between them because accidents due to expansion in summer can be avoided.
