11. Khristine is a member of a cheer dance group in their school and she is planning to practice. Which of the following exercises will she perform first? a. floor exercises b.warm-up c. cool down d. stretching 12. Which of the following is NOT an effect of warm-up? A. increase blood pressure B. increase mental alertness C. gently raised heart rate D. increase muscle elasticity 13. Which of the following is not true about warm-up? A. Increased blood flow and oxygen C. More muscle tension and pain B. It can help you increase flexibility D. It shows love to your body 14. What kind of exercise will you perform after doing your main activity? A. Warm-up B. stretching C. walking D. cool down 15. When is the right time to do warm-up? A. After engaging in physical activity C. before engaging to physical activities B. After stretching D. After cool down exercise​