Railways - Engineering

Q1:

Width of the top portion of a flat footed, rail, is

A 69.85 mm

B 63.50 mm

C 66.77 mm

D 136.52 mm

E none of these.

ANS:C - 66.77 mm

Can you explain how, the width of the top portion of a flat-footed rail is 66.77mm? Please explain.