What is the best title for this passage

A．it has a very large population
B．most streets don' t have names
C．people in Tokyo are bad at giving directions
D．too many famous companies have their offices there

A．effective walking lies in the gradual increase of speed
B．the same pace should be kept throughout the walking
C．one should not stop suddenly while walking fast
D．one should change one' s walking pattern every 5 minutes