Which of the following is correct description of the back stretch

I am not able to see the following!?

But, since I cant see the following I will give you an answer not according to "the following"

"Lie on your back with your knees bent and feet flat on the floor. Keeping your back flat on the floor, rotate your hips to the left, lowering your legs down to the floor until a gentle stretch is felt. Hold for 15 seconds. Return to the starting position. Repeat 9 more times."

Im sorry if this is about a different backstretch.

i think it would be b the increase in body temp

it'll be alright, just keep on going and keep your head up!