Directions: Write the letter of the correct answer on the blank 1. Which of the following is an example of a voluntary muscle? A heart muscle B. intestine muscle C. leg muscle C. vertebra D. stomacti musicie 2. What bone protects your brain? A cranium B. sternum 3. Where does the urine exit? D. breastbone A lungs B. kidney C: urethra 4. What is the process in which gases exchange in the body? Durinary bladder A digestion B. circulation C. respiration D. transformation 5. What organ of the excretory system filters the waste from the blood? A lungs B. kidney C. urethra D. urinary bladder​