Ginger (check out the facial expression on photo C) is doing cross-back lunges. Start with both legs together and then step back at angle. Keep remember to keep your knees at a 90 degree angel. Do this for both legs. Its simple yet burning.
Leg Side Plank Leg Lift
I know it is a mouthful but i cant think of another name. It is simple to do but tiring. Keep your elbow flat on the ground of course at a 90 degree angle. Keep your hips up off the ground, and the leg closest the ground bend for support. The top leg then kicks up off the ground in an upward motion. Stay in control