After tapping Choose Shots, first tap the edit button at the bottom of the screen below the photos on your Camera Roll.
Then find the shot for which you want to turn off movement, and tap that photo.
In the photo editing window, locate the button in the top-right corner that looks like a rectangle with arrows around it, and tap that button to toggle photo movement.
You will then see a message displayed telling you the status of movement for that photo.
Then tap Save to save the change you've made to your photo.