$A$ cyclist goes from one place to another and returns by the same route. He pedals his way uniformly with speed $u$ while going and with speed $v$ while returning. The average speed of his journey is

• A
  $\frac{u+v}{2}$
• B
  $\frac{u-v}{2}$
• C
  $\frac{1}{\frac{1}{2}(\frac{1}{u}+\frac{1}{v})}$
• D
  $\frac{1}{\frac{1}{2}(\frac{1}{u}-\frac{1}{v})}$