1. Read the statement carefully. Then encircle the best answer inside the pair of parentheses.
1. The ( heart, lung, skin ) is the largest organ of the human body.
2. The ( skeletal, digestive, integumentary ) system serves as the frame work of the body.
3. Mouth, esophagus, stomach, small and large intestines are in the (circulatory, digestive,
nervous system of the human body.
4. ( Lungs, Bronchi, Bronchioles) are the main organ of the respiratory system.
5. The bone, blood, vein ) is the liquid part that is constantly flowing throughout the body.
6. The ( neuron, brain, spinal cord) is the primary organ of the central nervous system
contained within the skull.​