A particle is projected from the ground with an initial speed of v at an angle $\theta$ with horizontal. The average velocity of the particle between its point of projection and highest
point of trajectory is 

• A

  $\frac{v}{2}\sqrt{1+{\cos }^2\theta }$

• B

  $\frac{v}{2}\sqrt{1+2{\cos }^2\theta }$

• C

  $\frac{v}{2}\sqrt{1+3{\cos }^2\theta }$

• D

  $v\cos \theta$